OC学习：OC中的可变字典NSMutableDictionary和字典的遍历

最新推荐文章于 2023-10-30 22:15:31 发布

TaLinBoy

最新推荐文章于 2023-10-30 22:15:31 发布

阅读量813

点赞数

CC 4.0 BY-SA版权

分类专栏： OC学习文章标签： OC中的字典 OC中的可变字典 OC中字典的遍历 NSMutableDictionary objective-c

本文链接：https://blog.youkuaiyun.com/TaLinBoy/article/details/47168991

OC学习专栏收录该内容

26 篇文章

订阅专栏

本文详细解析了可变与不可变字典的区别，包括如何使用新方法初始化可变字典、进行增删改操作、遍历字典及删除元素。同时，文章还演示了在遍历时如何删除字典元素。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

/*
          不可变字典,在不可变字典中没有
         */
        //可变字典继承了不可变字典的方法
        NSMutableDictionary *mDictionary0 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"value1",@"key1",@"value2",@"key2",@"value3",@"key3", nil];
        NSArray *arrayKey = @[@"key1",@"key2",@"key3"];
        NSArray *arrayValue = @[@"value1",@"value2",@"value3"];
        NSMutableDictionary *mDictionary1 = [NSMutableDictionary dictionaryWithObjects:arrayValue forKeys:arrayKey];

        //用新方法语句初始化可变字典是有警告的,如果对其进行增和删操作就会出错
//        NSMutableDictionary *mDictionary2 = @{@"key1":@"value1",@"key2":@"value2"};
//        [mDictionary2 setObject:@"value" forKey:@"key3"];
//        NSLog(@"新语句%@",mDictionary2[@"key1"]);    //此语句可以运行

        //增和改 (改是在增加的基础上替换，这说明字典的key是不可以相同的)
        [mDictionary1 setValue:@"value4" forKey:@"key4"];
        NSLog(@"mDictionary1 %@",[mDictionary1 objectForKey:@"key4"]);

        [mDictionary1 setValue:@"value4改" forKey:@"key4"];
        mDictionary1[@"key1"] = @"value1改";
        NSLog(@"mDictionary1 %@ , %@",mDictionary1[@"key1"],[mDictionary1 objectForKey:@"key4"]);

        //遍历字典的两种方法
        NSArray * allKey = [mDictionary1 allKeys];
        for (id obj in allKey) {
            NSLog(@"%@,%@",obj,[mDictionary1 objectForKey:obj]);

            //在便利字典的时候可以删除字典元素，但是在数组中却不行
            [mDictionary1 removeObjectForKey:obj];
            [mDictionary1 removeAllObjects];
        }
        NSArray *keyMdictionary1 = [mDictionary1 allKeys];
        NSEnumerator *enumer = [keyMdictionary1 objectEnumerator];
        id obj;
        while (obj = [enumer nextObject]) {
        NSLog(@"%@,%@",obj,[mDictionary1 objectForKey:obj]);

                //在便利字典的时候可以删除字典元素，但是在数组中却不行
            [mDictionary1 removeObjectForKey:obj];
            [mDictionary1 removeAllObjects];
    }
        //删
        [mDictionary1 removeObjectsForKeys:arrayKey];
        [mDictionary1 removeObjectForKey:@"key1"];
        [mDictionary1 removeAllObjects];