从 UIAlertController 按钮单击导航到 ViewController

Question

我对 Swift 开发很陌生，我尝试参考 Swift UIAlertController API，但在单击 UIAlertController 上的按钮后无法弄清楚如何导航到另一个 UIViewController。

我将不胜感激任何指针、帮助或解决此问题的方法。我的代码 sn-p 如下 -

@IBAction func showAlert() {

    let alertController = UIAlertController(title: "Disclaimer", message: "Disclaimer Text Here", preferredStyle: .Alert)


    let declineAction = UIAlertAction(title: "Decline", style: .Cancel, handler: nil)
    alertController.addAction(declineAction)

    let acceptAction = UIAlertAction(title: "Accept", style: .Default) { (_) -> Void in

        let secondVC = ViewController(nibName: "ViewController", bundle: nil)
        let navController = UINavigationController(rootViewController: secondVC)
        self.presentViewController(navController, animated: true, completion: nil)

    }
    alertController.addAction(acceptAction)

    presentViewController(alertController, animated: true, completion: nil)

}

我在这里尝试做的是单击按钮时显示免责声明 AlertController。如果选择了 "Decline" 按钮，则会执行取消操作，如果选择了 "Accept"，应用程序应该导航到导航控制器，然后我可以导航到其他视图控制器使用应用程序中的菜单。

之前我使用故事板将一个按钮链接到 NavigationController 以遍历我想要的 ViewController。现在我想以编程方式对 AlertController "Accept" 按钮执行相同的操作。

提前谢谢你。

Answer 1

您需要实现处理程序块以在选择操作时执行代码：

@IBActionfunc showAlert() {

    let alertController = UIAlertController(title: "Disclaimer", message: "Disclaimer Text Here", preferredStyle: .Alert)


    let declineAction = UIAlertAction(title: "Decline", style: .Cancel, handler: nil)
    alertController.addAction(declineAction)

    let acceptAction = UIAlertAction(title: "Accept", style: .Default) { (_) -> Void in

        let secondVC = SecondViewController(nibName: "SecondView", bundle: nil)
        let navController = UINavigationController(rootViewController: secondVC)
        self.presentViewController(navController, animated: true, completion: nil)
    }
    alertController.addAction(acceptAction)

    presentViewController(alertController, animated: true, completion: nil)

}

Answer 2

基本上，要将 UIAlertViewController 按钮链接到 UINavigationController 的 UIViewController，我们需要在具有 UIAlertViewController 的 UIViewController 与 UINavigationController 之间创建手动 segue。

请参阅此屏幕截图以了解如何执行上述操作 -

然后选择 UIViewController 和 UINavigationController 之间的链接。转到左侧边栏并选择属性检查器并命名标识符。

现在在您的代码中编写以下内容 -

@IBAction func showAlert() {

let alertController = UIAlertController(title: "Disclaimer", message: "Before using this teaching resource, you confirm that you agree:\n1. To obey the law regarding data protection and patient confidentiality.\n2. To us this app professionally and appropriately in clinical settings.\n3. This is for your personal use and you may not modify, distribute, publish, transfer any information obtained from this teaching resource without the developers' permission.\n4. In no event shall the developer be liable to you for any loss arising from your use of this resource.", preferredStyle: .Alert)

let declineAction = UIAlertAction(title: "Decline", style: .Cancel, handler: nil)
let acceptAction = UIAlertAction(title: "Accept", style: .Default) { (_) -> Void in    

    self.performSegueWithIdentifier("SomeSegue", sender: self) // Replace SomeSegue with your segue identifier (name)
}

alertController.addAction(declineAction)
alertController.addAction(acceptAction)

presentViewController(alertController, animated: true, completion: nil)
}

Answer 3

这就是处理程序块的用途。您应该在此块中进行所需的操作。

编辑：代码

let acceptAction = UIAlertAction(title: "Accept", style: .Default, handler:{  action in 
    //Write your code here
})

您可以使用此链接作为参考：http://www.appcoda.com/uialertcontroller-swift-closures-enum/