object-c之可变字典

  //初始化

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

        //添加键值对

        [dict setObject:@"1" forKey:@"a"];

        [dict setObject:@"2" forKey:@"b"];

        NSLog(@"dict---%@",dict);

        //删除键值对

        [dict removeObjectsForKeys:[NSArray arrayWithObjects:@"a",@"b", nil]];

         //删除键值对

        [dict removeObjectForKey:@"a"];

        NSLog(@"dict---%@",dict);

        //