iOS-OC-基础-NSDictionary常用方法

    /*=============================NSDictionary(不可变字典)的使用=========================*/
    
    //————————————————————————————————字典的创建————————————————————————————————
    
    // 前面的是值(value)，后面的是键(key)，一一对应
    // 方式一：
    NSDictionary *dic = [[NSDictionary alloc] initWithObjectsAndKeys:@"value",@"key",@"value1",@"key1", nil];
    NSLog(@"dic :%@",dic);
    
    // 方式二：
    NSDictionary *dic1 = [NSDictionary dictionaryWithObjectsAndKeys:@"value",@"key",@"value1",@"key1", nil];
    
    // 字典的value可以说任何对象类型
    NSArray *array = @[@"11",@"22",@"33"];
    NSDictionary *dic2 = [[NSDictionary alloc] initWithObjectsAndKeys:array,@"key" ,nil];
    NSLog(@"dic2 :%@",dic2);
    
    NSDictionary *dic3 = [[NSDictionary alloc] initWithObjectsAndKeys:dic2,@"dicKey", nil];
    NSLog(@"dic3 :%@",dic3);
    
    // 方式三：跟方式一区分,只能是不可变字典
    NSDictionary *dic4 = @{@"key":@"vlaue",@"key1":@"value1"};
    NSLog(@"dic4 :%@",dic4);
    
    
    //————————————————————————————————字典的常用方法—————————————————————————————
    
    // count 字典元素的个数，键值一起为一个元素
    NSUInteger len =  [dic4 count];
    NSLog(@"len = %ld",len);
    
    //objectForKey :根据key取对应的值，如果可以没有不会报错，返回的是null
    id obj = [dic3 objectForKey:@"dicKey"];
    NSLog(@"obj:%@",obj);
    
    //allKeys 获取字典的所有key,返回的是数组
    NSArray *allKeys = [dic4 allKeys];
    NSLog(@"allKeys :%@",allKeys);
    
    //allValues 获取字典的所有Value,返回的是数组
    NSArray *allValues = [dic4 allValues];
    NSLog(@"allValues: %@",allValues);
    
    //allKeysForObject 获取相同value的所有key
    NSDictionary *dic5 = @{@"key":@"value",@"key1":@"value"};
    NSArray *allKey = [dic5 allKeysForObject:@"value"];
    NSLog(@"allKey :%@",allKey);
    
    
    /*=============================NSMutableDictionary(可变字典)的使用=========================*/
    
    //————————————————————————————————可变字典的创建————————————————————————————————
    
    // 两种方式：
    NSMutableDictionary *mDic = [[NSMutableDictionary alloc] initWithObjectsAndKeys:@"abc",@"key",@"hhhh",@"key1", nil];
    
    NSMutableDictionary *mDic1 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"value",@"key",@"value1",@"key1", nil];
    
    //NSMutableDictionary *mDic2 = @{@"key":@"value",@"key1":@"value1"}; 错误:不能这样创建可变字典
    NSLog(@"mDic1:%@",mDic1);
    
    
    //————————————————————————————————可变字典的常用方法—————————————————————————————
    
    //setObject:forKey 给字典添加元素，修改元素
    [mDic1 setObject:@"value2" forKey:@"key2"];
    NSLog(@"mDic1:%@",mDic1);
    // 修改key 对应的元素
    [mDic1 setObject:@"kkkkk" forKey:@"key2"];
    
    //removeObjectForKey 移除指定键的元素
    [mDic1 removeObjectForKey:@"key"];
    NSLog(@"mDic1:%@",mDic1);
    
    // removeAllObjects 移除字典所有的元素
    [mDic1 removeAllObjects];
    NSLog(@"mDic1:%@",mDic1);
    
    // removeObjectsForKeys 移除一组键对应的元素
    NSArray *keys = [mDic1 allKeys];
    [mDic1 removeObjectsForKeys:keys];
    NSLog(@"mDic1:%@",mDic1);
    
    //setDictionary 将新字典替换旧字典
    [mDic1 setDictionary:mDic];
    NSLog(@"mDic1 :%@",mDic);
    
    
    /*===========================================字典的遍历===================================*/
    
    NSMutableDictionary *mDic3 = [[NSMutableDictionary alloc] initWithObjectsAndKeys:@"abc",@"key",@"etrtr",@"key1", nil];
    
    // 1、普通遍历
    NSArray *allkey = [mDic3 allKeys];
    for (int i = 0; i < mDic3.count; i++) {
        
        NSString *key = [allkey objectAtIndex:i];
        NSString *value = [mDic3 objectForKey:key];
        NSLog(@"---%@",value);
    }
    
    // 2、快速遍历 obj 是字典的key
    for (id obj in mDic3) {
        
        NSString *value = [mDic3 objectForKey:obj];
        NSLog(@"==%@",value);
    }
    
    // 3、block 遍历
    [mDic3 enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
        
        NSLog(@">>%@",key);
        NSLog(@">>%@",obj);
    }];

本文GitHub地址https://github.com/zhangkiwi/iOS_SN_NSDictionary