通过唯一的key找到对应的value,类似于Java中的Map
创建NSDictionary的方法
- + (id)dictionary
- + (id)dictionaryWithObject:(id)object forKey:(id<NSCopying>)key //作为key的对象需实现NSCopying协议
- + (id)dictionaryWithObjectsAndKeys:(id)firstObject,... //key和Object需成功出 , 如: NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys: @"v1", @"k1",@"v2",@"k2",nil]
- + (id)dictionaryWithDictionary:(NSDictionary *)dict
- + (id)dictionaryWithObjects:(NSArray *)objects forKeys:(NSArray *)keys
- - (id)initWithObjectsAndKeys:(id)firstObject,...
- - (id)initWithDictionary:(NSDictionary *)otherDictionary
- - (id)initWithObjects:(NSArray *)objects forKeys:(NSArray *)keys
- + (id)dictionaryWithContentsOfFile:(NSString *)path
- + (id)dictionaryWithContentsOfURL:(NSURL *)url
- - (id)initWithContentsOfFile:(NSString *)path
- - (id)initWithContentsOfURL:(NSURL *)url
NSDictionary常用方法
- - (NSUInteger) count //返回字典的key数
- - (BOOL)isEqualToDictionary:(NSDictionary *)otherDictionary //比较两个字典
- - (BOOL)writeToFile:(NSString *)path atomically:(BOOL)useAuxiliaryFile //将一个NSDictionary持久化到文件中去
NSDictionary访问key和value
- - (NSArray *)allKeys //返回所有的key
- - (NSArray *)allKeysForObject:(id)anObject //返回anObject元素对应的所有key
- - (NSArray *)allValues //返回所有的value
- - (id)objectForKey:(id)aKey //根据aKey返回对应的value
- - (NSArray *)objectsForKeys:(NSArray *)keys notFoundMarker:(id)marker //返回keys对应的所有value, 如果没有对应的value, 用marker代替
NSDictionary遍历
- 快速遍历: for (NSString *key in dict)
- 迭代器遍历:
- - (NSEnumerator *)keyEnumerator //key的迭代器
- - (NSEnumerator *)objectEnumerator //value的迭代器
- block遍历 [dict enumeratorKeysAndObjectsUsingBlock:^(id key, id object, BOOL *stop){ NSLog(@"key=%@, object=%@", key, object); }];
NSDictionary的key排序
- - (NSArray *)keyssortedByValueUsingComparator:(NSComparator)cmptr
- - (NSArray *)keysSortedByValueWithOptions:(NSSortOptions)opts usingComparator:(NSComparator)cmptr
- - (NSArray *)keysSortedByValueUsingSelector:(SEL)comparator
NSDictionary的使用,布布扣,bubuko.com
时间： 2024-10-13 00:48:15