NSDictionary Class Reference

        当你需要检索和管理以键值对形式存在的数据，可以使用NSDictionary和其子类NSMutableDictionary 声明的对象管理。
        在字典中称每一个键-值对为一个记录，每一个记录都是由一个key和一个对象组成。在字典中，key是独一无二的，也就是说，在一个字典中不会存在同样的key，但是key所对应的对象可以是同样的。key可以是任何类型的数据（只要它实现NSCopying协议），通常情况下，使用NSString作为Key。在字典中是不允许存在nil，如果你想在字典中存空值，可以使用NSNull。

NSDictionary创建的字典是不可变的，NSMutableDictionary创建的字典是可变的。
NSDictionary是线程安全的，NSMutableDictionary是线程不安全的。

内部结构图：

 

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创建

+ dictionary
+ dictionaryWithContentsOfFile:
+ dictionaryWithContentsOfURL:
+ dictionaryWithDictionary:
+ dictionaryWithObject:forKey:
+ dictionaryWithObjects:forKeys:
+ dictionaryWithObjects:forKeys:count:
+ dictionaryWithObjectsAndKeys:

#pragma mark 测试数据- (NSString *)testData {    // 获取应用中Document文件夹    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);    NSString *documentsDirectory = [paths objectAtIndex:0];    // 测试数据    NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"阳君", @"name", @"937447974", @"qq", nil];    NSString *filePath = [documentsDirectory stringByAppendingPathComponent:@"test.plist"];    [dict writeToFile:filePath atomically:YES]; // 输入写入    return filePath;}#pragma mark - 创建字典(+)- (void)testCreating {    // 空字典    NSDictionary *dictionary = [NSDictionary dictionary];    // 测试数据    NSString *filePath = [self testData];    // 通过文件路径创建字典    dictionary = [NSDictionary dictionaryWithContentsOfFile:filePath];    dictionary = [NSDictionary dictionaryWithContentsOfURL:[NSURL URLWithString:filePath]];    // 通过字典生成一个新的字典    dictionary = [NSDictionary dictionaryWithDictionary:dictionary];    // 生成只有一个键-值对的字典    dictionary = [NSDictionary dictionaryWithObject:@"value" forKey:@"key"];    // 根据两个数组合并生成包含多个键-值对的字典    NSArray *values = [NSArray arrayWithObjects:@"阳君", @"937447974", nil];    NSArray *keys = [NSArray arrayWithObjects:@"name", @"qq", nil];    dictionary = [NSDictionary dictionaryWithObjects:values forKeys:keys];    // 坑，不建议使用了    dictionary = [NSDictionary dictionaryWithObjects:&values forKeys:&keys count:2];    // 生成包含多个键-值对的字典。数据的顺序为value，key，nil    dictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"阳君", @"name", @"937447974", @"qq", nil];}

 

初始化

- init
- initWithContentsOfFile:
- initWithContentsOfURL:
- initWithDictionary:
- initWithDictionary:copyItems:
- initWithObjects:forKeys:
- initWithObjects:forKeys:count:
- initWithObjectsAndKeys:

#pragma mark 初始化字典(-)- (void)testInitializing {    // 空字典    NSDictionary *dictionary = [[NSDictionary alloc] init];    // 测试数据    NSString *filePath = [self testData];    // 通过文件路径创建字典    dictionary = [[NSDictionary alloc] initWithContentsOfURL:[NSURL URLWithString:filePath]];    dictionary = [[NSDictionary alloc] initWithContentsOfFile:filePath];    // 通过字典生成一个新的字典    dictionary = [[NSDictionary alloc] initWithDictionary:dictionary];    dictionary = [[NSDictionary alloc] initWithDictionary:dictionary copyItems:YES];    // 根据两个数组合并生成包含多个键-值对的字典    NSArray *values = [NSArray arrayWithObjects:@"阳君", @"937447974", nil];    NSArray *keys = [NSArray arrayWithObjects:@"name", @"qq", nil];    dictionary = [[NSDictionary alloc] initWithObjects:values forKeys:keys];    // 坑，不建议使用了    dictionary = [[NSDictionary alloc] initWithObjects:&values forKeys:&keys count:2];    // 生成包含多个键-值对的字典。数据的顺序为value，key，nil    dictionary = [[NSDictionary alloc] initWithObjectsAndKeys:@"阳君", @"name", @"937447974", @"qq", nil];}

 

个数

count Property

#pragma mark 计算个数- (void)testCountingEntries {    NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"阳君", @"name", @"937447974", @"qq", nil];    // 字典内的key-value个数,    NSUInteger count = dictionary.count; // output:2    NSLog(@"count:%lu", (unsigned long)count);}

 

比较

- isEqualToDictionary:

#pragma mark 比较- (void)testComparingDictionaries {    NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"阳君", @"name", @"937447974", @"qq", nil];    NSDictionary *dictionary1 = [NSDictionary dictionaryWithObjectsAndKeys:@"阳君", @"name", @"937447974", @"qq", nil];    // 比较字典中的数据是否一致    BOOL isEqual = [dictionary isEqualToDictionary:dictionary1];    NSLog(@"isEqualToDictionary:%d", isEqual);// out 1}

 

访问Keys和Values

allKeys Property
- allKeysForObject:
allValues Property
- objectForKey:
- objectForKeyedSubscript:
- objectsForKeys:notFoundMarker:
- valueForKey:

#pragma mark 访问键和值- (void)testAccessingKeysAndValues {    NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"阳君", @"name", @"阳君", @"name1", @"937447974", @"qq", nil];    // 所有的keys    NSArray *keys = dictionary.allKeys; // output:[qq,name,name1]    // 根据value获取keys，可能多个key指向    keys = [dictionary allKeysForObject:@"阳君"]; // output:[name,name1]    // 所有的keys    NSArray *values = dictionary.allValues; // output:[937447974, 阳君, 阳君]    // 根据key提取value,，    NSString *value = [dictionary objectForKey:@"name"]; // output:阳君    value = [dictionary valueForKey:@"name"]; // output:阳君    value = [dictionary objectForKeyedSubscript:@"name"];// output:阳君    // 根据多个key获取多个value,如果没找到    values = [dictionary objectsForKeys:keys notFoundMarker:@""];// output:[阳君, 阳君]}

 

遍历

- keyEnumerator:
- objectEnumerator
- enumerateKeysAndObjectsUsingBlock:
- enumerateKeysAndObjectsWithOptions:usingBlock:

#pragma mark 遍历- (void)testEnumerating {    NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"阳君", @"name", @"937447974", @"qq", nil];    // 遍历keys    NSEnumerator *enumerator = [dictionary keyEnumerator];    id key;    while (key = [enumerator nextObject]) {        NSLog(@"key:%@", key);    }    // 遍历values    enumerator = [dictionary objectEnumerator];    id value;    while (value = [enumerator nextObject]) {        NSLog(@"value:%@", value);    }    // 快速遍历key    for (id key in dictionary) {        id value = [dictionary objectForKey:key];        NSLog(@"%@=%@", key, value);    }    // key-value遍历    [dictionary enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {        NSLog(@"key:%@; value:%@", key, obj);        *stop = YES;// 当stop设为YES时，会停止遍历    }];    [dictionary enumerateKeysAndObjectsWithOptions:NSEnumerationReverse usingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {        NSLog(@"key:%@; value:%@", key, obj);        *stop = YES;// 当stop设为YES时，会停止遍历,必须设NSEnumerationReverse    }];}

 

排序

- keysSortedByValueUsingSelector:
- keysSortedByValueUsingComparator:
- keysSortedByValueWithOptions:usingComparator:

#pragma mark 排序- (void)testSorting {    NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"阳君", @"name", @"937447974", @"qq", nil];    // 使用Selector比较获取key, compare:由对象去实现    NSArray *array = [dictionary keysSortedByValueUsingSelector:@selector(compare:)];    // 使用block比较value,排序key    array = [dictionary keysSortedByValueUsingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {        return [obj1 compare:obj2];    }];    array = [dictionary keysSortedByValueWithOptions:NSSortStable usingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {        return [obj1 compare:obj2];    }];}

 

过滤

- keysOfEntriesPassingTest:
- keysOfEntriesWithOptions:passingTest:

#pragma mark 过滤- (void)testFiltering {    NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"阳君", @"name", @"937447974", @"qq", nil];    // 返回过滤后的keys    NSSet *set = [dictionary keysOfEntriesPassingTest:^BOOL(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {        // stop 是否停止过滤        // return 通过yes，禁止no        return YES;    }];    // 多核过滤    set = [dictionary keysOfEntriesWithOptions:NSEnumerationConcurrent passingTest:^BOOL(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {        // stop 是否停止过滤        // return 通过yes，禁止no        return YES;    }];}

 

存储

- writeToFile:atomically:
- writeToURL:atomically:

#pragma mark 存储- (void)testStoring {    NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"阳君", @"name", @"937447974", @"qq", nil];    NSString *filePath = [self testData];    // 根据路径存储字典    BOOL write = [dictionary writeToFile:filePath atomically:YES];    write = [dictionary writeToURL:[NSURL URLWithString:filePath] atomically:YES];    [dictionary fileCreationDate];}

 

访问文件属性

- fileCreationDate
- fileExtensionHidden
- fileGroupOwnerAccountID
- fileGroupOwnerAccountName
- fileHFSCreatorCode
- fileHFSTypeCode
- fileIsAppendOnly
- fileIsImmutable
- fileModificationDate
- fileOwnerAccountID
- fileOwnerAccountName
- filePosixPermissions
- fileSize
- fileSystemFileNumber
- fileSystemNumber
- fileType

#pragma mark 访问文件属性- (void)testAccessingFileAttributes {    NSString *filePath = [self testData];    // 不懂NSFileManager的可研读http://blog.csdn.net/y550918116j/article/details/49095679    NSError *error;    NSDictionary *dictionary = [[NSFileManager defaultManager] attributesOfItemAtPath:filePath error:&error];    NSLog(@"创建时间:%@", dictionary.fileCreationDate);    NSLog(@"是否可见:%d", dictionary.fileExtensionHidden);    NSLog(@"组ID:%@", dictionary.fileGroupOwnerAccountID);    NSLog(@"组名:%@", [dictionary fileGroupOwnerAccountName]);    NSLog(@"HFS编码:%u", (unsigned int)dictionary.fileHFSCreatorCode);    NSLog(@"HFS类型编码:%u", (unsigned int)dictionary.fileHFSTypeCode);    NSLog(@"是否只读:%d", dictionary.fileIsAppendOnly);    NSLog(@"是否可修改:%d", dictionary.fileIsImmutable);    NSLog(@"修改时间:%@", dictionary.fileModificationDate);    NSLog(@"所有者ID:%@", dictionary.fileOwnerAccountID);    NSLog(@"所有者名:%@", dictionary.fileOwnerAccountName);    NSLog(@"Posix权限:%lu", (unsigned long)dictionary.filePosixPermissions);    NSLog(@"大小:%llu", dictionary.fileSize);    NSLog(@"系统文件数量:%lu", (unsigned long)dictionary.fileSystemFileNumber);    NSLog(@"文件系统的数量:%ld", (long)dictionary.fileSystemNumber);    NSLog(@"文件类型:%@", dictionary.fileType);}

 

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参考文献

NSDictionary Class Reference
 

修订历史

时间 描述 2015-10-14 根据IOS 9的NSDictionary API总结

 

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