ios - 检查可选协议(protocol)方法是否在 Swift 中实现？

Question

我有一个快速协议(protocol):

@objc protocol SomeDelegate {

  optional func myFunction()

}

我上过的一门课:

weak var delegate: SomeDelegate?

现在我想检查 delegate 是否实现了 myFunction。

在 objective-c 中我可以这样做:

if ([delegate respondsToSelector:@selector(myFunction)]) { 
...
}

但这在 Swift 中是不可用的。

编辑:这不同于:What is the swift equivalent of respondsToSelector?我专注于类协议(protocol)而不是类。

如何检查我的委托(delegate)是否实现了可选方法？

Answer 1

根据 The Swift Programming Language:

You check for an implementation of an optional requirement by writing a question mark after the name of the requirement when it is called, such as someOptionalMethod?(someArgument). Optional property requirements, and optional method requirements that return a value, will always return an optional value of the appropriate type when they are accessed or called, to reflect the fact that the optional requirement may not have been implemented.

因此，目的不是让您检查该方法是否已实现，而是您无论如何都尝试调用它并获得可选的返回。