我还有一招。假设您有5个类，其中要应用注销警报。尝试使用swift类扩展。

文件-新建- Swift类-命名。

增加如下内容:

public extension UIViewController
{

    func makeLogOutAlert()
    {
        var refreshAlert = UIAlertController(title: "Log Out", message: "Are You Sure to Log Out ? ", preferredStyle: UIAlertControllerStyle.Alert)

        refreshAlert.addAction(UIAlertAction(title: "Confirm", style: .Default, handler: { (action: UIAlertAction!) in
            self.navigationController?.popToRootViewControllerAnimated(true)
        }))

        refreshAlert.addAction(UIAlertAction(title: "Cancel", style: .Default, handler: { (action: UIAlertAction!) in
            refreshAlert .dismissViewControllerAnimated(true, completion: nil)
        }))

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

实现使用:self.makeLogOutAlert()。希望能有所帮助。

不要在构造函数中提供otherbuttontitle。

let alertView = UIAlertView(title: "Oops!", message: "Something
happened...", delegate: nil, cancelButtonTitle: "OK")

alertView.show()

但我同意Oscar的观点，这个类在iOS 8中被弃用了，所以如果你只做iOS 8的应用程序，UIAlertView不会没有任何用途。否则上面的代码将工作。

@IBAction func Alert(sender: UIButton) {

    var alertView:UIAlertView = UIAlertView()
    alertView.title = "Alert!"
    alertView.message = "Message"
    alertView.delegate = self
    alertView.addButtonWithTitle("OK")

    alertView.show()

}

试试这个

显示UIAlertView在swift语言:-

Protocol UIAlertViewDelegate

let alert = UIAlertView(title: "alertView", message: "This is alertView", delegate:self, cancelButtonTitle:"Cancel", otherButtonTitles: "Done", "Delete")
alert.show()

显示UIAlertViewController在swift语言:-

let alert = UIAlertController(title: "Error", message: "Enter data in Text fields", preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))
self.presentViewController(alert, animated: true, completion: nil)

Swift 5上的SwiftUI。x和Xcode 11.x

import SwiftUI

struct ContentView: View {

    @State private var isShowingAlert = false

    var body: some View {
        VStack {
            Button("A Button") {

                self.isShowingAlert.toggle()
            }
            .alert(isPresented: $isShowingAlert) { () -> Alert in
                Alert(
                    title: Text("Alert"),
                    message: Text("This is an alert"),
                    dismissButton:
                        .default(
                            Text("OK"),
                            action: {
                                print("Dismissing alert")
                            }
                        )
                )
            }

        }
        .padding()
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

点击查看

@IBAction func testClick(sender: UIButton) {

  var uiAlert = UIAlertController(title: "Title", message: "Message", preferredStyle: UIAlertControllerStyle.Alert)
  self.presentViewController(uiAlert, animated: true, completion: nil)

  uiAlert.addAction(UIAlertAction(title: "Ok", style: .Default, handler: { action in
   println("Click of default button")
  }))

  uiAlert.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: { action in
   println("Click of cancel button")
  }))

}

完成两个按钮确定&取消