Objective-C是否支持泛型？ [英] Does Objective-C support Generics?

问题描述

我不知道Objective-C是否提供了对泛型的支持？

例如，考虑一个方法：

   - （void）sort：（NSMutableArray *）deck {
} 
  

我有什么办法让它只处理卡牌？

这样的东西是否可以执行？

   - （void）sort：（NSMutableArray< Card *>）deck {
} 
  

解决方案

您可以使用 introspection工具。

基本上，它意味着您可以检查数组中的所有对象是否都是种类（类A或其一个子类）或 （A类），或者如果对象符合协议或响应选择器（存在某种方法）。

   - （void）sort：（NSMutableArray *）deck {
 for（id obj in deck）{
 if（obj isKindOfClass ：[A class]]）{
 //这是正确的类
} 
} 
} 
  

您可以在 NSArray 上编写一个Category方法，用于在每个对象上检查此方法。

  BOOL allAreKindOfA = [array allObjectsAreKindOfClass：[A class]]; 
  

通常你实际上不需要这么多，因为你知道你放在一个集合中。

如果您需要检查数组中对象的类型或能力，这可能是一个指标，表明您的架构已损坏 / p>

---

另一个选项可以是 NSMutableArray 的子类，类。但请注意 NSMutableArray 和 NSArray ，因为这些是类集群，因此不容易子类化。

请注意：在我的其他answer 我创建了一个 NSMutableArray 子类，它使用一个块来测试，如果满足某个要求。如果你测试类成员资格，这将完全按照你想要的。使用第二个块进行错误处理。

I wonder whether Objective-C offers any support for generics?

For instance, consider a method:

-(void) sort: (NSMutableArray *) deck {
}

Is there any way for me to make it only deal with Deck of Cards?
Is something like this possible to enforce?

-(void) sort: (NSMutableArray <Card *>) deck {
}

解决方案

You can use the introspection tools offered by the objective-c runtime.

Basically, it means you can check if all objects in an array either are a kind of class (Class A or one subclass of it) or a member of class (class A), or if a objects conforms to a protocol or responds to a selector (a certain method is present).

-(void) sort: (NSMutableArray *) deck {
    for(id obj in deck){
        if(obj isKindOfClass:[A class]]){
            //this is of right class
        }
    }
}

You could write a Category method on NSArray that checkouts this on every object.

BOOL allAreKindOfA = [array allObjectsAreKindOfClass:[A class]];

Normally you actually don't need this very often, as you know what you put inside a collection.

If you need to check the type or ability of an object in a Array, this might be an indicator, that your Architecture is broken

---

Another option could be a subclass of NSMutableArray that only accepts certain classes. But be aware of the subclassing notes for NSMutableArray and NSArray, as these are Class-Clusters and therefore not easy to subclass.

Note: In my other answer I created a NSMutableArray subclass, that uses a block to test, if a certain requirement is fulfilled. If you test against class-membership, this will do exactly what you want. Use the second block for error handling.

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