iOS 正则表达式
正则表达式，又称正规表示法、常规表示法（英语：Regular Expression，在代码中常简写为regex、regexp或RE），计算机科学的一个概念。正则表达式使用单个字符串来描述、匹配一系列符合某个句法规则的字符串。在很多文本编辑器里，正则表达式通常被用来检索、替换那些符合某个模式的文本。
- 系统自带的, 如: NSPredicate, rangeOfString：option, NSRegularExpression
- RegexKitLite RegexKitLite 是一个轻量级的 Objective-C 的正则表达式库,支持 Mac OS X 和 iOS,使用 ICU 库开发。
至于RegexKitLite, 这里不做介绍。着重介绍系统自带的那几个办法。
PS: 阅读本文前提是您已经掌握了正则基本语法, 如果对正则还不太了解, 可以参考以下几个链接:
正则表达式学习链接：
- 55分钟学会正则表达式
- 揭开正则表达式的神秘面纱
- RegExLib.com(正则表达式库查询)
1. NSPredicate
简述：Cocoa框架中的NSPredicate用于查询，原理和用法都类似于SQL中的where，作用相当于数据库的过滤取。
<code class="language-objc hljs r 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;">NSPredicate *predicate = [NSPredicate predicateWithFormat:(NSString *), <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</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></ul>
其中, 常见的Format有:
(1) 比较运算符: >, <, ==, >=, <=, !=
例：@"number > 100"
(2) 范围运算符: IN, BETWEEN
例：@"number BETWEEN {1,5}" @"address IN {'shanghai','beijing'}"
(3) 字符串本身: SELF
例：@“SELF == ‘APPLE’"
(4) 字符串相关: BEGINSWITH, ENDSWITH, CONTAINS
例：@"name CONTAINS[cd] 'ang'" //包含某个字符串 @"name BEGINSWITH[c] 'sh'" //以某个字符串开头 @"name ENDSWITH[d] 'ang'" //以某个字符串结束注:[c]不区分大小写 [d]不区分发音符号即没有重音符号 [cd]既不区分大小写，也不区分发音符号。
(5) 通配符: LIKE
例：@"name LIKE[cd] '*er*'" //*代表通配符,Like也接受[cd]. @"name LIKE[cd] '???er*'"
(6) 正则表达式: MATCHES
例：NSString *regex = @"^A.+e$"; //以A开头，e结尾 @"name MATCHES %@",regex
至于如何使用呢? 下面举几个例子:
(a) 对NSArray进行过滤, 帅选出包含”ang”的项
<code class="language-objc 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;">NSArray</span> *array = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSArray</span> alloc]initWithObjects:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"beijing"</span>, @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"shanghai"</span>, @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"guangzou"</span>, @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"wuhan"</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;">NSString</span> *string = @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"ang"</span>; NSPredicate *pred = [NSPredicate predicateWithFormat:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"SELF CONTAINS %@"</span>, string]; <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>, [array filteredArrayUsingPredicate:pred]);<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 打印结果:</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// (</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// shanghai,</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// guangzou</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// )</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></ul>
(b) 对NSDate进行筛选
<code class="language-objc 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-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//日期在十天之内:</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDate</span> *endDate = [<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDate</span> date]; <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSTimeInterval</span> timeInterval= [endDate timeIntervalSinceReferenceDate]; timeInterval -=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3600</span>*<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">24</span>*<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>; <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDate</span> *beginDate = [<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDate</span> dateWithTimeIntervalSinceReferenceDate:timeInterval]; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//对coredata进行筛选(假设有fetchRequest)</span> NSPredicate *predicate_date = [NSPredicate predicateWithFormat:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"date >= %@ AND date <= %@"</span>, beginDate,endDate]; [fetchRequest setPredicate:predicate_date];</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></ul>
OK, NSPredicate的功能很多, 也很强大。这里暂时就点到此, 感兴趣的可以自己一一试验。 下面举两个例子说明一下如何使用正则。
<code class="language-objc 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-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 判断是否是有效邮箱</span>- (<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span>)isValidateEmail:(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> *)email{ <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> *regex = @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"</span>; NSPredicate *predicate = [NSPredicate predicateWithFormat:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"SELF MATCHES %@"</span>, regex]; <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> [predicate evaluateWithObject:email];}<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 判断字符串首字母是否为字母</span>- (<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span>)isStartedWithWord:(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> *)aString{ <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> *regex = @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"[A-Za-z]+"</span>; NSPredicate *predicate = [NSPredicate predicateWithFormat:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"SELF MATCHES %@"</span>, regex]; <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> [predicate evaluateWithObject:aString];}</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><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li></ul>
2. 利用rangeOfString：option：直接查找
<code class="language-objc 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> *searchText = @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"// Do any additional setup after loading the view, typically from a nib."</span>; <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSRange</span> range = [searchText rangeOfString:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"(?:[^,])*\\."</span> options:NSRegularExpressionSearch]; <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (range<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.location</span> != <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSNotFound</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>, [searchText substringWithRange:range]); }<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 打印结果:</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// typically from a nib.</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></ul>options中设定NSRegularExpressionSearch就是表示利用正则表达式匹配，会返回第一个匹配结果的位置。
3. 使用正则表达式类
详细了解: iOS 正则表达式 NSRegularExpression
上面那篇文章总结的很不错. 这里简单再举个例子:
<code class="language-objc 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> *searchText = @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"// Do any additional setup after loading the view, typically from a nib."</span>; <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSError</span> *error = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">NULL</span>; NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"(?:[^,])*\\."</span> options:NSRegularExpressionCaseInsensitive error:&error]; NSTextCheckingResult *result = [regex firstMatchInString:searchText options:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span> range:NSMakeRange(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, [searchText length])]; <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;">"%@\n"</span>, [searchText substringWithRange:result<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.range</span>]); }<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 打印结果:</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// typically from a nib.</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>使用系统的正则表达式类（NSRegularExpression）会返回匹配的多个结果。
针对以上3种方式, 做一个小小总结
第一种匹配需要学习NSPredicate的写法，需要查阅苹果相关技术文档；
如果只关心第一个匹配的结果，第二种匹配较为简洁；
如果需要匹配多个结果，同时匹配多次，第三种方式效率会更高。
常用正则表达式
参考: IOS常用正则表达式
表达式 | 作用 | [\u4e00-\u9fa5]匹配中文字符[^\x00-\xff]匹配双字节字符(包括汉字在内)\n\s*\r匹配空白行<(\S*?)[^>]*>.*?|<.*? />匹配HTML标记^\s*|\s*$匹配首尾空白字符\w+([-+.]\w+)*@\w+([-.]\w+)*.\w+([-.]\w+)*匹配Email地[a-zA-z]+://[^\s]*匹配网址URL\d{3}-\d{8}|\d{4}-\d{7}匹配国内电话号码,匹配形式如 0511-4405222 或 021-87888822[1-9]\d{5}(?!\d)匹配中国邮政编码\d+.\d+.\d+.\d+匹配ip地址
