Swift 显示自定义消息的 UIAlertController

Question

我有一个 ViewController class，其唯一目的是显示一条带有自定义消息和标题的警报消息，该消息通过自定义初始化消息传入。一旦视图出现，就会在 viewDidLoad 中完成此操作。然而，我的问题是，当涉及到这个视图时，它会弹出并永远停留在这个视图中，而不是仅仅将视图放在另一个视图之上。我不确定如何解决这个问题。这是我的 alertVC class

的代码

import UIKit

class AlertVC: UIViewController {

  var myMessage: String?
  var myTitle: String?

  override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
  }

  override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
  }


  override func viewDidAppear(animated: Bool){
    let alertController = UIAlertController(title: myTitle, message: myMessage, preferredStyle: .Alert)
    let OKAction = UIAlertAction(title: "OK", style: .Default) {
        (action: UIAlertAction) in print("Youve pressed OK Button")
    }
    alertController.addAction(OKAction)
    self.presentViewController(alertController, animated: true, completion: nil)
  }

  convenience init(title: String, message: String){
    self.init()
    self.myTitle = title
    self.myMessage = message
  }
}

这是我如何为此创建 object 并尝试展示它的代码。

let alert = AlertVC(title: "Error", message: "error")
presentViewController(alert, animated: true, completion: nil)

感谢任何帮助，如果您需要更多信息，请发表评论。谢谢！

Answer 1

如果 AlertVC 的唯一目的是显示 UIAlertController，你为什么不在你之前的 ViewController 上显示 UIAlertController？

所以你在哪里写的：

let alert = AlertVC(title: "Error", message: "error")
presentViewController(alert, animated: true, completion: nil)

替换为：

let alertController = UIAlertController(title: myTitle, message: myMessage, preferredStyle: .Alert)
let OKAction = UIAlertAction(title: "OK", style: .Default) {
    (action: UIAlertAction) in print("Youve pressed OK Button")
}
alertController.addAction(OKAction)
self.presentViewController(alertController, animated: true, completion: nil)

编辑：阅读您的评论后，我了解到您想避免多次输入相同的代码。我已经做了一些快速研究，你似乎 shouldn't subclass UIAlertController，所以也许扩展可能有用？类似于：

extension UIAlertController{
    class func customAlertController(title : String, message : String) -> UIAlertController{
        let alertController = UIAlertController(title: title, message: message, preferredStyle: .Alert)
        let OKAction = UIAlertAction(title: "OK", style: .Default) {
            (action: UIAlertAction) in print("Youve pressed OK Button")
        }
        alertController.addAction(OKAction)
        return alertController
    }
}

然后替换为：

let alert = AlertVC(title: "Error", message: "error")
presentViewController(alert, animated: true, completion: nil)

与：

    let alert = UIAlertController.customAlertController("Error!", message: "error")
    self.presentViewController(alert, animated: true) {

    }

Answer 2

为什么不直接 extension？

extension UIViewController {

  func presentAlert(withTitle title: String, message : String) {
    let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
    let OKAction = UIAlertAction(title: "OK", style: .default) { action in
        print("You've pressed OK Button")
    }
    alertController.addAction(OKAction)
    self.present(alertController, animated: true, completion: nil)
  }
}

并用

调用它

presentAlert(withTitle: "Error", message: "error")

任意 UIViewController class

Answer 3

@vadian 在 Swift 3 中的回答将完成处理程序添加到警报控制器关闭。

extension UIViewController {

    func presentAlertWithTitle(title: String, message : String, onDismiss: SimpleCompletionBlock? = nil)
    {
        let alertController = UIAlertController(title: title, message: message, preferredStyle: .Alert)

        let OKAction = UIAlertAction(title: "OK", style: .Default) {
            (action: UIAlertAction) in print("Youve pressed OK Button")

            onDismiss?()
        }

        alertController.addAction(OKAction)
        self.presentViewController(alertController, animated: true, completion: nil)
    }
}

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