IOS SDK详解之NSDictionary

原创Blog，转载请注明出处 
blog.csdn.net/hello_hwc

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前言：本文将要讲述的内容有 
1.NSDictionary 以及 NSMutableDictionary 概述 
2.常用属性方法举例（不常用的本文不会涉及）

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一 NSDictionary/NSMutableDictionary概述 
NSDictionary提供了一种key－value的数据存储方式。总的来说，任何对象都可以作为key，只要其遵循NSCopying协议。其中，key不能相同（由isEqual来判断）。key和value都不能为nil，如果要表达一个空的值，用NSNull。NSDictionary中的值不可变。 
NSMutableDictionary是NSDictionary的子类，是可变的字典。

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二 NSDictionary常用的属性方法举例

2.1 创建和初始化 
创建兼初始化

<code class="hljs css has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">(<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">instancetype</span>)<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">dictionaryWithContentsOfFile</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:(NSString</span> *)<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">path</span>(<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">instancetype</span>)<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">dictionary</span>;(<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">instancetype</span>)<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">dictionaryWithDictionary</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:(NSDictionary</span> *)(<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">instancetype</span>)<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">dictionaryWithObjects</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:(NSArray</span> *)<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">objects</span>   <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">forKeys</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:(NSArray</span> *)<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">keys</span>(<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">instancetype</span>)<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">dictionaryWithObjectsAndKeys</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:(id)firstObject</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>

初始化

<code class="hljs erlang has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-pp" style="box-sizing: border-box;">-<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(<span class="hljs-variable" style="box-sizing: border-box;">NSDictionary</span> *)</span>init;-<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(<span class="hljs-variable" style="box-sizing: border-box;">NSDictionary</span> *)</span>initWithContentsOfFile:<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(<span class="hljs-variable" style="box-sizing: border-box;">NSString</span> *)</span>path;-<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(<span class="hljs-variable" style="box-sizing: border-box;">NSDictionary</span> *)</span>initWithDictionary:<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(<span class="hljs-variable" style="box-sizing: border-box;">NSDictionary</span> *)</span>;-<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(<span class="hljs-variable" style="box-sizing: border-box;">NSDictionary</span> *)</span>initWithObjects:<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(<span class="hljs-variable" style="box-sizing: border-box;">NSArray</span> *)</span>objects   forKeys:<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(<span class="hljs-variable" style="box-sizing: border-box;">NSArray</span> *)</span>keys;-<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(<span class="hljs-variable" style="box-sizing: border-box;">NSDictionary</span> *)</span>initWithObjectsAndKeys:<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(id)</span>firstObject;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>

就个人而言，我比较习惯后一种。当然，快捷创建的方式不要忘记了 
符号

@{}

举例：

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * emptyDic = [<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> dictionary];    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * firstDic = @{@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"value"</span>,                                @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"first"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1"</span>};    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * secondDic = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> alloc] initWithObjectsAndKeys:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"value1"</span>,@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key1"</span>,@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"value2"</span>,@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key2"</span>,<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">nil</span>];</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

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2.2 count 
返回key－value对的个数

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * dic = @{@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key1"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1"</span>,                           @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key2"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"2"</span>};    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%d"</span>,dic<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.count</span>);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

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2.3 isEqualToDictionary比较两个dictionary内容是否一样。

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * dic1 = @{@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key1"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1"</span>,                           @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key2"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"2"</span>};    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * dic2 = @{@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key2"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"2"</span>,                            @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key1"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1"</span>};    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> ([dic1 isEqualToDictionary:dic2]) {        <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Equal contents"</span>);    }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul>

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2.4 objectForKey: 和valueForKey 由属性获得内容

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * dic1 = @{@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key1"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1"</span>,                           @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key2"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"2"</span>};    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,[dic1 objectForKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key1"</span>]);    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,[dic1 valueForKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key2"</span>]);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

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2.5 allKeys 和 allValues 获得所有的key/value

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * dic1 = @{@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key1"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1"</span>,                           @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key2"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"2"</span>};    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSArray</span> * keys = [dic1 allKeys];    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSArray</span> * values = [dic1 allValues];</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

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2.6 enumerateKeysAndObjectsUsingBlock 用Block的方式遍历

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">这里的stop决定了是否停止遍历。<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * dic1 = @{@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key1"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1"</span>,                           @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key2"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"2"</span>};[dic1 enumerateKeysAndObjectsUsingBlock:^(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span> key, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span> obj, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span> *stop) {        <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@=>%@"</span>,[key description],[obj description]);    }];</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul>

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2.7 排序 
keysSortedByValueUsingSelector: 
keysSortedByValueUsingComparator : 
keysSortedByValueWithOptions: usingComparator: 
返回Keys的数组，顺序按照value排序顺序。

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">  <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * numsDic = @{@(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>):@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"second"</span>,                               @(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>):@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"first"</span>,                               @(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>):@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"thrid"</span>};    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * strDic = @{@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"id_1"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"first"</span>,                              @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"id_3"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"thrid"</span>,                              @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"id_2"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"second"</span>};    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSArray</span> * numsSortedKeys = [numsDic keysSortedByValueUsingSelector:<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@selector</span>(compare:)];    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSArray</span> * strSortedKyes = [strDic keysSortedByValueUsingComparator:^NSComparisonResult(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span> obj1, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span> obj2) {        <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * str1 = obj1;        <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * str2 = obj2;        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> [str1 compare:str2];    }];    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,numsSortedKeys<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.description</span>);    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,strSortedKyes<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.description</span>);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li></ul>

输出

2015-02-09 22:04:12.070 DictonaryExample[1037:23292] ( 
1, 
2, 
3 
) 
2015-02-09 22:04:12.070 DictonaryExample[1037:23292] ( 
“id_1”, 
“id_2”, 
“id_3” 
)

---

2.8 过滤 
keysOfEntriesPassingTest： 
返回keys的集合，这些keys符合参数block的约束

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">  <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * numsDic = @{@(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>):@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"second"</span>,                               @(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>):@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"first"</span>,                               @(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>):@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"thrid"</span>};  NSSet * filteredKyes = [numsDic keysOfEntriesPassingTest:^<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span> key, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span> obj, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span> *stop) {        <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span> result = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">NO</span>;        <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSNumber</span> * numKey = key;        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (numKey<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.integerValue</span> > <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>) {            result =  <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">YES</span>;        }        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> result;    }];    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,filteredKyes<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.description</span>);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

输出

2015-02-09 22:09:50.800 DictonaryExample[1099:25241] {( 
3 
)}

---

2.9写到文件 
writeToFile:atomically 
writeToURL:atomically

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">   <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">YES</span>) firstObject] ;    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * fileName = @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"file"</span>;    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * filePath = [path stringByAppendingPathComponent:fileName];    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> * dic = @{@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"value"</span>};    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span> result = [dic writeToFile:filePath atomically:<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">YES</span>];    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (result) {        <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Success"</span>);    }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>

---

2.10Description－常常用来debug输出dictionary的内容。 
在之前已经举例好多了，这里不再赘述

---

三 NSMutableDictionary的额外方法 
3.1 添加元素

<code class="hljs erlang has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-pp" style="box-sizing: border-box;">- <span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(void)</span>setObject:<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(id)</span>anObject           forKey:<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(id<<span class="hljs-variable" style="box-sizing: border-box;">NSCopying</span>>)</span>aKey- <span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(void)</span>setValue:<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(id)</span>value          forKey:<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(<span class="hljs-variable" style="box-sizing: border-box;">NSString</span> *)</span>key- <span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(void)</span>setDictionary:<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(<span class="hljs-variable" style="box-sizing: border-box;">NSDictionary</span> *)</span>otherDictionary</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>

注意，使用KVC的时候，key一定要是NSString。第三个函数是删除之前的元素，然后把otherDictionary元素放到当前dic中。 
举例

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSMutableDictionary</span> * dic = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSMutableDictionary</span> alloc] initWithObjectsAndKeys:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"object"</span>,@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key"</span>, <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">nil</span>];    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,dic<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.description</span>);    [dic setDictionary:@{@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"otherKey"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"otherValue"</span>}];    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,dic<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.description</span>);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

输出

2015-02-09 22:31:21.417 DictonaryExample[1232:31666] { 
key = object; 
} 
2015-02-09 22:31:21.418 DictonaryExample[1232:31666] { 
otherKey = otherValue; 
}

3.2删除元素

<code class="hljs erlang has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-pp" style="box-sizing: border-box;">- <span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(void)</span>removeObjectForKey:<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(id)</span>aKey- <span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(void)</span>removeAllObjects- <span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(void)</span>removeObjectsForKeys:<span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(<span class="hljs-variable" style="box-sizing: border-box;">NSArray</span> *)</span>keyArray</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

比较容易忽视的是第三个，删除一组key。 
举例

<code class="hljs lua has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> NSDictionary * dic = @{@(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>):@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"first"</span>,                           @(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>):@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"second"</span>,                           @(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>):@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"thrid"</span>};    NSMutableDictionary * mutableDic = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">[[NSMutableDictionary alloc] initWithDictionary:dic];    [mutableDic removeObjectsForKeys:@[@(1),@(2)]]</span>;    NSLog(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,mutableDic.description);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul>

输出

<code class="hljs fix has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-attribute" style="box-sizing: border-box;">2015-02-09 22:34:13.112 DictonaryExample[1273:32793] {    3 </span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;"> thrid;}</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li></li></ul>