从 NSArray 获取单个属性的 NSArray [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场景.

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.

如何从具有 Person 对象的 NSArray 中获取仅包含一个属性的 NSArray?

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

类似:

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

我有一个解决方案，可以编写一个 for 循环并填写 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 为您处理此问题

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 值的数组

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

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