ios - 协议(protocol)要求委托(delegate)继承自 UIViewController

Question

我有一个看起来像这样的协议(protocol) ShareDelegate:

protocol ShareDelegate : class {
    func share(event: EventJSONModel, skipToTime time: CMTime?, view: UIView, completion: @escaping () -> ())
}

extension ShareDelegate where Self: UIViewController {
    func share(event: EventJSONModel, skipToTime time: CMTime? = nil, view: UIView, completion: @escaping () -> ()) {

    }
}

然后当我将其用作委托(delegate)时:

weak var delegate: ShareDelegate?

然后调用委托(delegate)函数:

delegate?.share(event: event, view: view, completion: completion)

它给我以下错误

“ShareDelegate”要求“ShareDelegate”继承自“UIViewController”

如果我删除扩展的 skipToTime time: CMTime? 部分，它就可以正常工作。为什么？？

Answer 1

问题是协议(protocol)和默认实现之间的接口(interface)不同。

协议(protocol):

func share(event: EventJSONModel, skipToTime time: CMTime?, view: UIView, completion: @escaping () -> ())

扩展名:

func share(event: EventJSONModel, skipToTime time: CMTime? = nil, view: UIView, completion: @escaping () -> ())

所以你已经在扩展中声明了 skipToTime 是可选的，并且有一个默认值，所以当调用它并跳过那个值时，你专门调用了 UIViewController 的版本

更新:

您应该能够限制 ShareDelegate 协议(protocol)的使用，以便它仅适用于 UIViewControllers，如下所示:

protocol ShareDelegate: class where Self: UIViewController {
    func share()
}