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()
    }
}

  // UIAlertView is deprecated. Use UIAlertController 
  // title = title of the alert view.
  // message = Alert message you want to show.
  // By tap on "OK" , Alert view will dismiss.

 UIAlertView(title: "Alert", message: "Enter Message here.", delegate: nil, cancelButtonTitle: "OK").show()

从UIAlertView类:

// UIAlertView已弃用。使用UIAlertController 将UIAlertControllerStyleAlert改为preferredStyle

在iOS 8上，你可以这样做:

let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.Default, handler: nil))
self.presentViewController(alert, animated: true, completion: nil)

UIAlertController是一个单独的类，用于创建和交互我们在ios8中知道的UIAlertViews和UIActionSheets。

编辑:处理动作:

alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: { action in
    switch action.style{
    case .Default:
        print("default")
        
    case .Cancel:
        print("cancel")
        
    case .Destructive:
        print("destructive")
    }
}}))

为Swift 3编辑:

let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.default, handler: nil))
self.present(alert, animated: true, completion: nil)

为Swift 4.x编辑:

let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { action in
    switch action.style{
        case .default:
        print("default")
        
        case .cancel:
        print("cancel")
        
        case .destructive:
        print("destructive")
        
    }
}))
self.present(alert, animated: true, completion: nil)

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

你可以使用这个简单的扩展与n个按钮和相关的动作swift4以上

extension UIViewController {
    func popupAlert(title: String?, message: String?, actionTitles:[String?], actions:[((UIAlertAction) -> Void)?]) {
        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
        for (index, title) in actionTitles.enumerated() {
            let action = UIAlertAction(title: title, style: .default, handler: actions[index])
            alert.addAction(action)
        }
        self.present(alert, animated: true, completion: nil)
    }
}

你可以这样使用它，

self.popupAlert(title: "Message", message: "your message", actionTitles: ["first","second","third"], actions:[
            {action1 in
                //action for first btn click
            },
            {action2 in
                //action for second btn click
            },
            {action3 in
                //action for third btn click
            }, nil]) 

    class Preview: UIViewController , UIAlertViewDelegate
    {
        @IBAction func MoreBtnClicked(sender: AnyObject)
        {
            var moreAlert=UIAlertView(title: "Photo", message: "", delegate: self, cancelButtonTitle: "No Thanks!", otherButtonTitles: "Save Image", "Email", "Facebook", "Whatsapp" )
            moreAlert.show()
            moreAlert.tag=111;
        }

        func alertView(alertView: UIAlertView, didDismissWithButtonIndex buttonIndex: Int)
        {
            if alertView.tag==111
            {
                if buttonIndex==0
                {
                    println("No Thanks!")
                }
                else if buttonIndex==1
                {
                    println("Save Image")
                }
                else if buttonIndex == 2
                {
                    println("Email")
                }
                else if buttonIndex == 3
                {
                    println("Facebook")
                }
                else if buttonIndex == 4
                {
                    println("Whatsapp")
                }
            }
        }
    }