ios - 更改嵌套 NSMutableDictionary 中的值

Question

我有一个 NSMutableDictionary，我想将元素的值更改为它。

//My dictionary:

{
    objectId = 8ED998yWd1;
    cardInfo =     {
        state = published; //THIS!
        price = 40;
        color = red;
        }   
};

我尝试了几种方法，但值没有改变，像这样:

[dictionary setObject:@"reserved" forKey:@"state"]; //nope

或者这个:

[dictionary setValue:@"reserved" forKeyPath:@"cardInfo.state"]; //nope

或者:

[[dictionary objectForKey:@"cardInfo"] setObject:@"reserved" forKey:@"state"]; //no

还有这个:

[dictionary setObject:@"reserved" forKey:[[dictionary objectForKey:@"cardInfo"] objectForKey:@"state"]];

如何将对象“状态”从“已发布”更改为“保留”？

谢谢!

Answer 1

假设 dictionary 和 cardInfo 都是 NSDictionary 实例:

您可以获取嵌套字典的可变副本，修改适当的值，然后将修改后的字典写回到“顶级”字典中，如下所示:

NSMutableDictionary *mutableDict = [dictionary mutableCopy];
NSMutableDictionary *innerDict = [dictionary[@"cardInfo"] mutableCopy];
innerDict[@"state"] = @"reserved";
mutableDict[@"cardInfo"] = innerDict;
dictionary = [mutableDict copy];

我猜你可以把它压缩成一行，但这将是一条难看的线。

编辑:

如果外部和内部字典都已经可变，那么当然会稍微简化事情:

NSMutableDictionary *innerDict = dictionary[@"cardInfo"];
innerDict[@"state"] = @"reserved";
dictionary[@"cardInfo"] = innerDict;