OC基础知识--字典处理方法

不可变字典

【初始化】

1.  value   —  key

NSDictionary * dict =[[NSDictionary alloc]initWithObjectsAndKeys:@"one",@"1",@"two",@"2", nil];

2.批量设置键值对    value — key

NSArray * arr1 = @[@"1",@"2"];

NSArray * arr2 = @[@"one",@"two"];

NSDictionary * dict1 = [[NSDictionary alloc]initWithObjects:arr1 forKeys:arr2];

3.  key : value

NSDictionary * dict3 = @{@"1":@"one",@"2":@"two",@"3":@"one"};

4.通过key拿到value

NSString * str1 = [dict3 objectForKey:@"1"];

5.拿到所有的key

NSArray * arr3 = [dict3 allKeys];

6.拿到所有的Value

arr3 = [dict3 allValues];

7.拿到所有相同value的key  （key一定唯一存在 value不唯一）

arr3 = [dict3 allKeysForObject:@"one"];

【遍历】

1.普通遍历

for (int i = 0; i < [arr3 count]; i ++) {

NSLog(@"%@",[dict3 objectForKey:arr3[i]]);

}

2.快速遍历

for (NSString * str in dict3) {

//str 是key

NSLog(@"%@",dict3[str]);

}

【可变字典】

【初始化】

1.带参数的初始化

NSMutableDictionary * mDict = [NSMutableDictionary dictionaryWithDictionary:dict3];

2.设置键值对    value ———— key

[mDict setValue:@“one” forKey:@“1”];

3.删除键值对

[mDict removeObjectForKey:@"one"];

4.删除所有键值对

[mDict removeAllObjects];

5.根据key值 批量删除键值对

[mDict removeObjectsForKeys:arr3];

6.重置

[mDict setDictionary:dict3];