ios - 如何将协议(protocol)类型添加为 subview

Question

所以我写了一个简单的协议(protocol):

protocol PopupMessageType{
    var cancelButton: UIButton {get set}
    func cancel()
}

并有一个自定义 View :

class XYZMessageView: UIView, PopupMessageType {
...
}

然后我现在有:

class PopUpViewController: UIViewController {

    //code...

    var messageView : CCPopupMessageView!
    private func setupUI(){
    view.addSubview(messageView)

    }

}

但是我想做的是:

class PopUpViewController: UIViewController {

    //code...

    var messageView : PopupMessageType!
    private func setupUI(){
    view.addSubview(messageView) // ERROR

    }

}

我得到的错误:

Cannot convert value of type 'PopupMessageType!' to expected argument type 'UIView'

编辑:我正在使用 Swift 2.3!

Answer 1

将属性 messageView 的类型更改为 (UIView & PopupMessageType)!

我是说

class PopUpViewController: UIViewController {

    //code...

    var messageView : (UIView & PopupMessageType)!
    private func setupUI(){
    view.addSubview(messageView) // ERROR

    }

}