直接访问Objective-C中的嵌套字典值 [英] Directly accessing nested dictionary values in Objective-C

问题描述

有没有办法直接访问Objective-C中外部数组的内部数组？例如，对外部数据源的调用返回以下对象：

Is there a way to directly access an inner-array of an an outer array in Objective-C? For example, a call to an external data source returns the following object:

{
bio = "this is the profile.bio data";
"first_name" = John;
"last_name" = Doe;
location =     {
    name = "Any Town, Any State";
};
metadata =    {
    pictures =    {
        picture = "https://picture.mysite.com/picture.jpeg";
    }
}
}

我想要能够访问，例如location.name或metadata.pictures.picture数据。然而，点符号似乎不起作用。例如：

I want to be able to access, for example, the location.name or the metadata.pictures.picture data. Dot notation, however, does not seem to work. For example:

_gfbLocation = [result objectForKey:@"location.name"];
_gfbPicture = [result objectForKey:@"metadata.pictures.picture"];

我能够访问这些数据的唯一方法是首先设置内部数组的内容对象

The only way I have been able to access this data is by first setting the contents of the inner arrays to objects. Thoughts?

推荐答案

对于这样的嵌套键，您可以使用 keyPath 。 keyPath只是一些连接点的键。您可以使用它们从支持键值编码的对象中检索嵌套值 - 包括像您这样的NSDictionary对象。所以在你的情况下，这应该工作：

For nested keys like that you can use a keyPath. A keyPath is just a series of keys joined with dots. You can use them to retrieve nested values from objects that support Key-Value Coding - including NSDictionary objects like yours. So in your case this should work:

[result valueForKeyPath:@"location.name"];

有关键值编码的更多详细信息，请参阅Apple的 ./apple.com / library / ios /＃documentation / Cocoa / Conceptual / KeyValueCoding / KeyValueCoding.html％23 // apple_ref / doc / uid / 10000107irel =noreferrer

For more detail on Key-Value Coding, see Apple's Key-Value Coding Programming Guide.

另请参见这个相关的StackOverflow问题。

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