iOS-NSDictionary、NSMutableDictionary

1. NSDictionary

1.1 初始化方法

//直接赋值。
NSDictionary *dic = @{@"key-1":@"value-1", @"key-2":@"value-2"};

+ (instancetype)dictionary;//这个多用于创建无数据的可变字典。

+ (instancetype)dictionaryWithObject:(ObjectType)object forKey:(KeyType )key;
NSDictionary *dic = [NSDictionary dictionaryWithObject:@"value-1" forKey:@"key-1"];

+ (instancetype)dictionaryWithDictionary:(NSDictionary *)dict;

+ (instancetype)dictionaryWithObjects:(NSArray *)objects forKeys:(NSArray> *)keys;
NSDictionary *dic = [NSDictionary dictionaryWithObjects:@[@"value-1", @"value-2"] forKeys:@[@"key-1", @"key-2"]];

- (instancetype)initWithObjectsAndKeys:(id)firstObject, ... NS_REQUIRES_NIL_TERMINATION;
NSDictionary *dic = [[NSDictionary alloc]initWithObjectsAndKeys:@"value-1", @"key-1", @"value-2", @"key-2", nil];

- (instancetype)initWithDictionary:(NSDictionary *)otherDictionary;

- (instancetype)initWithObjects:(NSArray *)objects forKeys:(NSArray> *)keys;
NSDictionary *dic = [[NSDictionary alloc]initWithObjects:@[@"value-1", @"value-2"] forKeys:@[@"key-1", @"key-2"]];

1.2 NSDictionary属性

//字典键值对的个数
NSUInteger count;
NSInteger count = dic.count;

//字典所有Key的数组
NSArray *allKeys;
NSArray *array = dic.allKeys;

//字典所有Value的数组
NSArray *allValues;
NSArray *array = dic.allValues;

1.3 常用方法

//取值方法
NSString *str = dic[@"key-1"];//直接取值（常用）
- (nullable ObjectType)objectForKey:(KeyType)aKey;
NSString *str = [dic objectForKey:@"key-1"];
 
//枚举器，用于枚举器遍历方法
- (NSEnumerator *)keyEnumerator;//key枚举器
NSEnumerator *keyEnumerator = [dic keyEnumerator];

- (NSEnumerator *)objectEnumerator;//object枚举器
NSEnumerator *objectEnumerator = [dic objectEnumerator];
 
//获取字典中anObject对应的所有key,字典中key是唯一的，但value不唯一，一个value可以对应多个key。
- (NSArray *)allKeysForObject:(ObjectType)anObject;
NSDictionary *dic = @{@"key-1":@"value-1", @"key-2":@"value-2", @"key-3":@"value-1"};
NSArray *array = [dic allKeysForObject:@"value-1"];
//array = @[@"key-1", @"key-3"];
 
//判断两个字典是否一样
- (BOOL)isEqualToDictionary:(NSDictionary *)otherDictionary;

2. NSMutableDictionary

2.1 常用方法

//添加键值对
- (void)setObject:(ObjectType)anObject forKey:(KeyType )aKey;
[mutableDic setObject:@"value-1" forKey:@"key-1"];

//根据aKey删除键值对
- (void)removeObjectForKey:(KeyType)aKey;
[mutableDic removeObjectForKey:@"key-1"];
 
//删除所有数据
- (void)removeAllObjects;
[mutableDic removeAllObjects];
 
//根据keyArray删除多个键值对
- (void)removeObjectsForKeys:(NSArray *)keyArray;
[mutableDic removeObjectsForKeys:@[@"key-1", @"key-2"]];
 
//添加otherDictionary整个字典的数据
- (void)addEntriesFromDictionary:(NSDictionary *)otherDictionary;
[mutableDic addEntriesFromDictionary:dic];
 
//重新设置
- (void)setDictionary:(NSDictionary *)otherDictionary;
[mutableDic setDictionary:dic];

3. 遍历方法

3.1 for 循环遍历

NSDictionary *dic = @{@"key-1":@"value-1", @"key-2":@"value-2"};
NSArray *keyArray = dic.allKeys;
for (int i = 0; i < keyArray.count; i++) {
    NSString *key = keyArray[i];
    NSString *value = dic[key];
}

3.2 for in 快速枚举

for (NSString *key in dic) {
    NSString *value = dic[key];
}

3.3 NSEnumerator 枚举器遍历

NSEnumerator *keyEnumerator = [dic keyEnumerator];
NSString *key;
while (key = [keyEnumerator nextObject]) {
    NSString *value = dic[key];
}
//因为字典是无序的，所以也没有正序和逆序的区别

3.4 block遍历

[dic enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
    NSLog(@"%@:%@", key, obj);
}];

//多线程并发遍历
[dic enumerateKeysAndObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
    NSLog(@"%@:%@-%@", key, obj, [NSThread currentThread]);
}];