Cocoa/Objective-C 中是否有类似通用列表的东西? [英] Is there anything like a generic list in Cocoa / Objective-C?

问题描述

我在 C# 中真正喜欢的是泛型列表.只能包含一种类型的对象的列表.Cocoa/Objective-C 中是否有类似通用列表的东西?到目前为止，我只知道 NSArray 谁将获取指向任何对象的指针.

What I really like in C# are generic lists. A list that can contain only one type of objects. Is there something like a generic list in Cocoa/Objective-C? As far I only know NSArray who will take a pointer to any object.

推荐答案

在 Cocoa 应用程序中想要这个通常是设计薄弱的标志.

Wanting this in a Cocoa app is often a sign of a weak design.

NSArray 是不可变的，因此它不会获取指向任何对象的指针"，并且在交给您时可能已经包含正确的对象.我假设您更担心的是 NSMutableArray 您认为代码的其他部分可能会添加错误类型的对象.但是看看 Cocoa 本身；将可变数组作为类设计的一部分公开是非常罕见的.

NSArray is immutable, so it will not "take a pointer to any object" and presumably already contains the correct objects when handed to you. What I assume you're more worried about is an NSMutableArray where you think other parts of your code might add the wrong sort of object. But have a look at Cocoa itself; it's incredibly rare to expose a mutable array as part of a class's design.

相反，您通常公开一个 NSArray 和一些修改该数组的方法.类似的东西:

Instead, you generally expose an NSArray and a couple of methods for modifying that array. Something along the lines of:

@class Foo : NSObject
- (NSArray *)bars;
- (void)addBar:(Bar *)bar;
- (void)removeBar:(Bar *)bar;
@end

这通常会简单地通过编译器警告来阻止错误的对象插入，然后当然你可以在 -addBar: 和 -removeBar: 中添加断言，如果你愿意

This generally stops wrong objects being inserted simply by having a compiler warning, and then of course you can add assertions within -addBar: and -removeBar: if you wish too.

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