swift - 使用 Swift 在 switch/case 语句中设置 UIViewController

Question

我正在尝试加载基于按钮按下的 View 。我想我可以在下面做这样的事情，我定义了一个通用的 UIViewController，然后将它设置为 switch/case 语句中的特定 UIViewController，但它显然不能这样工作。我做错了什么？

@objc func menuButton(sender: UIButton) {
    var view: UIViewController!
    switch sender.tag {
        case 0:
            view = MenuViewController()
            view.menuType = .Account
        case 1:
            view = MenuViewController()
            view.menuType = .Sync
        case 2:
            view = AuthViewController()
            view.menuType = .Auth
        default: break
    }
    self.navigationController?.pushViewController(view, animated: true)
}

Answer 1

如果我没记错的话，编译器应该会报错:

Value of type 'UIViewController' has no member 'menuType'

这里有几个选项可以解决这个问题:

解决方案一

使用转换

@objc func menuButton(sender: UIButton) {
    var view: UIViewController!
    switch sender.tag {
        case 0:
            view = MenuViewController()
            (view as? MenuViewController())?.menuType = .Account
        case 1:
            view = MenuViewController()
            (view as? MenuViewController())?.menuType = .Sync
        case 2:
            view = AuthViewController()
            (view as? AuthViewController())?.menuType = .Auth
        default: break
    }
    self.navigationController?.pushViewController(view, animated: true)
}

方案二

创建协议(protocol)MenuProtocol

protocol MenuProtocol {
    var menuType: MenuType { get set }
}

并使 MenuViewController 和 AuthViewController 实现该协议(protocol)。然后您可以执行以下操作:

@objc func menuButton(sender: UIButton) {
    var view: (UIViewController & MenuProtocol)!
    switch sender.tag {
        case 0:
            view = MenuViewController()
            view.menuType = .Account
        case 1:
            view = MenuViewController()
            view.menuType = .Sync
        case 2:
            view = AuthViewController()
            view.menuType = .Auth
        default: break
    }
    self.navigationController?.pushViewController(view, animated: true)
}