oc之可变字典创建 添加 删除 遍历

//创建字典
        NSMutableDictionary *mutableDic=[[NSMutableDictionary alloc]
                                         initWithObjectsAndKeys:@"jay",@"name",
                                                                @"22",@"age",
                                                                @"f",@"gender", nil];
        NSLog(@"%@",mutableDic);
        //创建空的字典
        NSMutableDictionary *mutab=[NSMutableDictionary dictionary];
        //将字典mutableDic复制到mutab中
        [mutab setDictionary:mutableDic];

 

//添加键值对的方式（向字典内添加一组键值）
        NSDictionary *dict1=[NSDictionary dictionaryWithObject:@"166" forKey:@"height"];
        [mutableDic addEntriesFromDictionary:dict1];
        NSLog(@"%@",mutableDic);
        //直接添加方式如果key存在时，就是修改对应的value值，如果不存在则是添加
        [mutableDic setValue:@"66" forKey:@"weight"];
        NSLog(@"%@",mutableDic);

//将字典中对应key的值删除
        [mutableDic removeObjectForKey:@"weight"];
        //删除一组key对应的value值
        [mutableDic removeObjectsForKeys:@[@"height",@"age"]];
        //删除所有value值
        [mutableDic removeAllObjects];

//遍历
        //(1) 1.先找到所有key 2.计算key的个数，用来循环 3.通过key的数组找到对应key的值 (这种方法较慢)
        NSArray *keyss=[mutableDic allKeys];
        NSUInteger count=[mutableDic count];
        for(int i=0;i<count;i++){
            id key=[keyss objectAtIndex:i];
            NSLog(@"%@",[mutableDic objectForKey:key]);
        }
        //(2) 快速枚举  for in 语句 注意不能在改循环内对数组进行删除和增加 （即不能改变数组成员个数）
        for(id key in mutableDic){
            id obj=[mutableDic objectForKey:key];
            NSLog(@"%@",obj);
        }
        //(3)通过枚举对象 进行枚举
        //1.将字典里的key转成枚举对象，用于遍历
        NSEnumerator *keyenums=[mutableDic keyEnumerator];
        id key;
        while(key){                        //直到key为空时结束循环
            id obj=[mutableDic objectForKey:key];//通过key取到value
            NSLog(@"%@",obj);
            key=[keyenums nextObject];     //将枚举中下一个对象赋值给key
        }