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 = @[@"",@"",@""];
     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 = ; 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