从NSArray获取NSArray的单个属性 [英] Getting an NSArray of a single attribute from an NSArray

问题描述

我正面临一个非常常规的情况。

I am facing a very regular scenario.

我有一个NSArray，它有一个自定义类型的对象，比如Person。 Person类具有以下属性：firstName，lastName和age。

I have an NSArray which has object of a custom type, say Person. The Person class has the attributes: firstName, lastName and age.

如何从NSArray中获取一个只包含Person对象的NSArray？

How can I get an NSArray containing only one attribute from the NSArray having Person objects?

类似于：

NSArray *people;
NSArray *firstNames = [people getArrayOfAttribute:@"firstName" andType:Person.Class]

我有一个编写for循环的解决方案并填写firstNames数组但我不想这样做。

I have a solution of writing a for loop and fill in the firstNames array but I don't want to do that.

推荐答案

NSArray将使用KVC为您处理此事

NSArray will handle this for you using KVC

NSArray *people ...;
NSArray *firstName = [people valueForKey:@"firstName"];

这将为您提供数组中每个条目的firstName值数组

This will give you an array of the firstName values from each entry in the array

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