Question

我有一个NSMutableDictionary我想要更改元素的值。

//My dictionary:

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

我尝试了几种方法，但价值不会改变，如下所示：

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

或者这个：

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

或那：

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

和此：

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

如何将对象“state”从“已发布”更改为“已保留”？

谢谢！

Answer 1

假设dictionary和cardInfo都是NSDictionary个实例：

您可以获得嵌套字典的可变副本，修改相应的值，并将修改后的字典写回“顶级”字典，如下所示：

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

我猜你可以在一行中挤压它，但这将是一条难看的线。

修改

如果外部字典和内部字典都已经mutable，那么可以简化一些事情，当然：

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

更改嵌套的NSMutableDictionary中的值

1 个答案: