Question

我想为我的项目创建一个可重用的UIAlertController类。我尝试了以下代码。但我的警报没有显示。我的代码或任何代码帮助有什么问题。这是我的警报类

class AlertView: NSObject {

 class func showAlert(view: UIViewController , message: String){

        let alert = UIAlertController(title: "Warning", message: message, preferredStyle: UIAlertControllerStyle.Alert)
        alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))
        view.presentViewController(alert, animated: true, completion: nil)
    }
}

我在另一个视图控制器中调用它，如

class ViewController: UIViewController {

  override func viewDidLoad() {
      super.viewDidLoad()
      AlertView.showAlert(self, message: "Test alert")
      // Do any additional setup after loading the view, typically from a nib.
   }
}

Answer 1

你可以使用Anbu Karthiks答案。作为替代方案，我使用Swift 2s协议扩展来显示警报。

import UIKit

protocol Alertable { }
extension Alertable where Self: UIViewController {

func showAlert(title title: String, message: String) {

    let alertController = UIAlertController(title: title, message: message, preferredStyle: .Alert)

    let okAction = UIAlertAction(title: "OK", style: .Cancel) { _ in }
    alertController.addAction(okAction)

    DispatchQueue.main.async {       
       self.view?.window?.rootViewController?.presentViewController(alertController, animated: true, completion: nil)
    }
}

 func showAlertWithSettings(title title: String, message: String) {

    let alertController = UIAlertController(title: title, message: message, preferredStyle: .Alert)

    let okAction = UIAlertAction(title: "OK", style: .Cancel) { _ in }
    alertController.addAction(okAction)

    let settingsAction = UIAlertAction(title: "Settings", style: .Default) { _ in
       guard let url = NSURL(string: UIApplicationOpenSettingsURLString) else { return }
        UIApplication.sharedApplication().openURL(url)
    }
    alertController.addAction(settingsAction)

    DispatchQueue.main.async {       
         self.view?.window?.rootViewController?.presentViewController(alertController, animated: true, completion: nil)
   }
}

现在，在您需要显示警报的viewControllers中，您只需遵守协议

class ViewController: UIViewController, Alertable { }

并调用类似

的方法

showAlert(title: "Alert title", message: "Alert message")

好像它们是viewController本身的一部分。

Swift SpriteKit: Best practice to access UIViewController in GameScene

注意：正如成员在评论中所说，viewDidLoad可能会很快显示警告。尝试稍微延迟或使用ViewDidAppear

希望这有帮助

Answer 2

在main_queue

中显示您的提醒

class AlertView: NSObject {

    class func showAlert(view: UIViewController , message: String) {
        let alert = UIAlertController(title: "Warning", message: message, preferredStyle: UIAlertControllerStyle.Alert)
        alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))

        dispatch_async(dispatch_get_main_queue(), {
            view.presentViewController(alert, animated: true, completion: nil)
        })
    }
}

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        AlertView.showAlert(self, message: "Test alert")
        // Do any additional setup after loading the view, typically from a nib.
    }
}

Answer 3

在swift 3＆amp; 4

中可重复使用ALERT

class AlertView: NSObject {
    class func showAlert(view: UIViewController , title: String , message: String){
        let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
        alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil))
        view.present(alert, animated: true, completion: nil)
    }
}

 //How to use?
 //Alert.showAlert(view: self, title: "Alert!", message: "Reusable Alert")

如何创建可重用的UIAlertcontroller？

3 个答案: