//key 和 value 都属于(id)对象类型

    //key常用字符串NSString来表示

    //存储数值型 一般可用 NSString

    //int  age ->@(age)

     //  [dic[name] intValue];

     //   @()-->转成NSNumber 类型

     //     intValue

    //value可以使任意对象(NSString  NSArrray , dog  )

    //NSDictionary 一旦创建不能修改增加删除

#pragma mark 字典的创建

   NSDictionary * dic = [[NSDictionary alloc]initWithObjectsAndKeys:

      @"value1",@"key1",

      @"value2",@"key2",

      @"value2",@"key3",nil];

        NSLog(@"%@",dic);

    NSDictionary * dic1 = [NSDictionary dictionaryWithObjectsAndKeys:@"value1",@"key1", nil];

    //用字典创建字典

    NSDictionary * dic2 = [[NSDictionary alloc]initWithDictionary:dic];

        NSLog(@"%@",dic2);

    //xcode4.6

    //格式: key : value 多个元素之间用,分隔

    //用NSLog打印字典是不支持汉字的转码

    // \U5bd2\U4ed2;

    NSDictionary * dic3 =

        @{@"key1":@"value1",

          @"key2":@"value2",

          @"key3":@"value3",

          @"key4":@"value2"

          };

#pragma mark 查看键的个数

    NSUInteger  num = [dic2 count];

        NSLog(@"%lu",num);

#pragma mark 通过key找value

  NSString * str =  [dic3 objectForKey:@"key1"];

    //xcode4.6

   NSString * str2 = dic3[@"key2"];

        NSLog(@"%@",str);

        NSLog(@"%@",str2);

#pragma mark  获取所有key 所有value

    NSArray * keyArray  =  [dic3 allKeys];

    NSArray * valueArray = [dic3 allValues];

        NSLog(@"keys = %@",keyArray);

        NSLog(@"values = %@",valueArray);

#pragma mark 查看一个value对应多个key

     NSArray * array =  [dic3  allKeysForObject:@"value2"];

        NSLog(@"%@",array);

#pragma mark 可变字典

#pragma mark 创建可变字典

NSMutableDictionary * mutDic = [[NSMutableDictionary alloc] init];

NSDictionary * dic4 =

        @{@"key1":@"value1",

          @"key2":@"value2",

          @"key3":@"value3",

          @"key4":@"value2"

          };

NSMutableDictionary * mutDic2 = [[NSMutableDictionary alloc]initWithDictionary:dic4];

#pragma mark 增加

        //key不重复是增加键值对

        [mutDic2 setObject:@"value3"

                    forKey:@"key5"];

        //保证Key不重复 key必须唯一

        //通过查询key的obj 是否为 ==NULL

//        if ([mutDic2 objectForKey:@"key5"]== NULL) {

//            

//        }

        NSDictionary * dic5 = @{@"key_1":@"value1",

              @"key_2":@"value2"};

    [mutDic2 addEntriesFromDictionary:dic5];

        NSLog(@"%@",mutDic2);

#pragma mark 删除

        //通过key删除值

    [mutDic2 removeObjectForKey:@"key_1"];

        NSLog(@"%@",mutDic2);

    NSArray * array2 = @[@"key_2",@"key2",@"key4"];

    [mutDic2 removeObjectsForKeys:array2];

        NSLog(@"%@",mutDic2);

//        [mutDic2 removeAllObjects];

//        NSLog(@"%@",mutDic2);

#pragma mark 修改

        //key 已存在是修改当前value的值

        [mutDic2 setObject:@"hhhh" forKey:@"key1"];

        NSLog(@"%@",mutDic2);

        //完全覆盖掉当前字典中所有的值

        [mutDic2 setDictionary:dic2];

        NSLog(@"%@",mutDic2);

    }

iosOC不可变字典和可变字典