ios - setValue:forKey：设置指定索引的所有值

Question

我知道这将是非常基本的，但我似乎无法弄清楚。

我有NSMutableArray两个索引，每个索引都有NSMutableDictionary几个值。我想更改一个索引中的一个值，[[anArray objectAtIndex:index] setValue:newValue forKey:someKey];但这会更改所有索引中该键的值。我不确定发生了什么。

谢谢您的帮助。

Answer 1

您的代码没有问题[[anArray objectAtIndex:index] setValue:newValue forKey:someKey];

你应该添加NSMutableDictionary这样的

NSMutableArray *myArray = [[NSMutableArray alloc] init];

NSMutableDictionary *dict1 = [[NSMutableDictionary alloc] initWithObjectsAndKeys:@"dict1value1", @"key1", @"dict1value2", @"key2", nil];


[myArray addObject:[dict1 copy]];

[myArray addObject:dict1];

[[myArray objectAtIndex:1] setValue:@"NEW VALUE" forKey:@"key2"];

NSLog(@"%@",[myArray objectAtIndex:0]);
NSLog(@"%@",[myArray objectAtIndex:1]);

或者

   NSMutableArray *myArray = [[NSMutableArray alloc] init];

    NSMutableDictionary *dict1 = [[NSMutableDictionary alloc] initWithObjectsAndKeys:@"dict1value1", @"key1", @"dict1value2", @"key2", nil];

    NSMutableDictionary *dict2 = [[NSMutableDictionary alloc] initWithObjectsAndKeys:@"dict2value1", @"key1", @"dict2value2", @"key2", nil];

    [myArray addObject:dict1];

    [myArray addObject:dict2];

    [[myArray objectAtIndex:1] setValue:@"NEW VALUE" forKey:@"key2"];

    NSLog(@"%@",[myArray objectAtIndex:0]);
    NSLog(@"%@",[myArray objectAtIndex:1]);

输出

{
    key1 = dict1value1;
    key2 = dict1value2;
}

{
    key1 = dict1value1;
    key2 = "NEW VALUE";
}

Answer 2

在添加字典之前复制它

不要添加它 N 次，因为您将拥有一个包含 N 个指向同一个字典的指针的数组

id d1 = @{.....}.mutableCopy;
id d2 = d1.mutableCopy;

NSArray *array = @[d1,d2];

然后使用 setValueForKey 左右独立编辑键/值