符合两种协议的Swift通用类型 [英] Swift generic type conforming to two protocols

问题描述

我在我的类中有一个泛型方法，我想要一个符合 UIViewController 和 UIPickerViewDelegate 。我怎样才能做到这一点？我想这样做：

  func foo< T：UIViewController，UIPickerViewDelegate> （#viewController：T）{} 
  

但是这段代码不能识别 UIPickerViewDelegate 。我还想过使用管道 | 而不是逗号，但这更糟糕，编译器不接受。
是否可以这样做，还是必须为类和协议做2个参数？或者是否有更好的解决方法？

感谢您的帮助和圣诞快乐：] / div>

您的代码：

  func foo< T：UIViewController，UIPickerViewDelegate> （#viewController：T）{} 
  

声明 2 泛型参数：

• T 它是 UIViewController 。它被用作 viewController 参数类型。


• UIPickerViewDelegate 它是不限。
  

相反，您应该使用Where Clause，如：

  func foo< T：UIViewController where T：UIPickerViewDelegate> （#viewController：T）{} 
  

I have a generic method in one of my classes where I want to have a generic type conforming to UIViewController and UIPickerViewDelegate. How can I do that? I thought of doing this:

func foo<T: UIViewController, UIPickerViewDelegate> (#viewController: T) {}

But this code doesn't "recognize" the UIPickerViewDelegate. I also thought of using the pipe | instead of the comma but this is even worse, the compiler doesn't accept that. Is it possible to do this or do I have to do 2 parameters for the class and the protocol? Or is there a nicer workaround?

Thanks for your help and Merry Christmas :]

解决方案

Your code:

func foo<T: UIViewController, UIPickerViewDelegate> (#viewController: T) {}

declares 2 generics parameters:

• T which is UIViewController. And it's used as viewController parameter type.
• UIPickerViewDelegate which is Any. And it's not used.

Instead, you should use "Where Clause", like:

func foo<T: UIViewController where T:UIPickerViewDelegate> (#viewController: T) {}

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