ios - swift 如何传递 UIViewController 类型的参数

Question

我有这个功能来呈现登录/注册模态视图 Controller 。传递的参数必须是 UIViewController<AuthViewControllerDelegate> (UIViewController 代表方法，AuthViewControllerDelegate 代表方法)

static func checkAuthError(controller: UIViewController<AuthViewControllerDelegate>, err: NSError) {
    if err.code == 401 {
        let authViewController = viewControllerWithIdentifier("AuthViewController") as! AuthViewController
        authViewController.delegate = controller
        controller.presentViewController(authViewController, animated: true, completion: nil)
    }
}

但我无法传递 objective c 样式类型。我是否必须通过不同类型的同一 Controller 两次？

Answer 1

您可以为方法参数选择类或协议(protocol)类型，并有条件地将其转换为另一个:

func checkAuthError(controller: UIViewController, err: NSError) {
    ...
    if authDelegate = controller as? AuthViewControllerDelegate {
        ...
    }
}

或者，您可以使用泛型类型约束:

func checkAuthError<T: UIViewController where T: AuthViewControllerDelegate>(controller: T, err: NSError) {
    ...
}