Objective - C NSDictionary不可变字典和NSMutableDictionary可变字典

Posted 2020-06-14

 

//创建一个不可变的字典对象

    //便利构造器创建

    NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:@"zhonger", @"name2", @"taixu", @"name1", @"caicai", @"name3", nil];

 

    //初始化方法

    //先给value 再给key

    NSDictionary *dic1 = [[NSDictionary alloc]initWithObjectsAndKeys:@"zhonger", @"name2", @"taixu", @"name1", @"caicai", @"name3", nil];

    

    NSDictionary *dic2 = [[NSDictionary alloc] initWithObjects:@[@"name1", @"name2", @"name3"] forKeys:@[@"zhonger", @"name2", @"taixu"]];

    

    //笑笑语法

    //key 在前 value在后

    NSDictionary *dic3 = @{@"name1":@"zhanger", @"name2":@"caicai", @"name3":@"fufu"};

    

    //获取字典中键值对的个数，以及获取所有的key和所有的value；

    NSUInteger count = [dic3 count];

    

    NSArray *arr = [dic3 allKeys];

    

    NSLog(@"dic3 allkeys is %@",arr);

    

    NSLog(@"dic3 allvalue is %@",[dic3 allValues]);

    

    //获取字典中的某个value值，通过key

    NSString *string = [dic3 objectForKey:@"name2"];

   

    NSArray *allkeys = [dic3 allKeys];

    for (int i = 0; i < [allkeys count]; i ++) {

        NSLog(@" %@",[dic3 objectForKey:allkeys[i]]);

    }

    

    

    //创建可变字典对象，初始化方法，便利构造器，字面量

    NSMutableDictionary *mDic = [[NSMutableDictionary alloc] initWithCapacity:0];

    NSMutableDictionary *mDic1 = [NSMutableDictionary dictionaryWithCapacity:0];

    NSMutableDictionary *mDic2 = [@{@"key1":@"zhangsan", @"key2":@"lisi", @"key3":@"wangwu"}mutableCopy];

    NSLog(@"mDic2 is %@",mDic2);

    

    //增加键值对的方法 setObject:forkey:

    [mDic2 setObject:@"liumazi" forKey:@"key4"];

    NSLog(@"mDic2 is %@",mDic2);

    

    //删除键值对的方法,删除之后,key和value都不存在了

    //removeObjectForKey:

    [mDic2 removeObjectForKey:@"key2"];

    NSLog(@"mDic2 is %@",mDic2);

    

    //移除所有的键值对

    [mDic2 removeAllObjects];

    NSLog(@"mDic2 is %@",mDic2);

    

    //修改键值对的方法和增加键值对的方法是一样的。。

    [mDic2 setObject:@"zhangsan" forKey:@"key1"];

    NSLog(@"mDic2 is %@",mDic2);

    [mDic2 setObject:@"lisi" forKey:@"key1"];

    NSLog(@"mDic2 is %@",mDic2);

    //字典中的Key是不能重复的 但是value可以重复，并且字典是一个无序集合