One Button

class ViewController: UIViewController {



    @IBAction func showAlertButtonTapped(_ sender: UIButton) {



        // create the alert

        let alert = UIAlertController(title: "My Title", message: "This is my message.", preferredStyle: UIAlertController.Style.alert)



        // add an action (button)

        alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))



        // show the alert

        self.present(alert, animated: true, completion: nil)

    }

}

Two Buttons

class ViewController: UIViewController {



    @IBAction func showAlertButtonTapped(_ sender: UIButton) {



        // create the alert

        let alert = UIAlertController(title: "UIAlertController", message: "Would you like to continue learning how to use iOS alerts?", preferredStyle: UIAlertController.Style.alert)



        // add the actions (buttons)

        alert.addAction(UIAlertAction(title: "Continue", style: UIAlertAction.Style.default, handler: nil))

        alert.addAction(UIAlertAction(title: "Cancel", style: UIAlertAction.Style.cancel, handler: nil))



        // show the alert

        self.present(alert, animated: true, completion: nil)

    }

}

Three Buttons

class ViewController: UIViewController {



    @IBAction func showAlertButtonTapped(_ sender: UIButton) {



        // create the alert

        let alert = UIAlertController(title: "Notice", message: "Lauching this missile will destroy the entire universe. Is this what you intended to do?", preferredStyle: UIAlertController.Style.alert)



        // add the actions (buttons)

        alert.addAction(UIAlertAction(title: "Remind Me Tomorrow", style: UIAlertAction.Style.default, handler: nil))

        alert.addAction(UIAlertAction(title: "Cancel", style: UIAlertActio.nStyle.cancel, handler: nil))

        alert.addAction(UIAlertAction(title: "Launch the Missile", style: UIAlertAction.Style.destructive, handler: nil))



        // show the alert

        self.present(alert, animated: true, completion: nil)

    }

}

Handling Button Taps

The handler was nil in the above examples. You can replace nil with a closure to do something when the user taps a button. For example:

alert.addAction(UIAlertAction(title: "Launch the Missile", style: UIAlertAction.Style.destructive, handler: { action in



    // do something like...

    self.launchMissile()



}))

Notes

• Multiple buttons do not necessarily need to use different UIAlertAction.Style types. They could all be .default.


• For more than three buttons consider using an Action Sheet. The setup is very similar. Here is an example.
  

You can create a UIAlert using the standard constructor, but the 'legacy' one seems to not work:

let alert = UIAlertView()

alert.title = "Alert"

alert.message = "Here's a message"

alert.addButtonWithTitle("Understood")

alert.show()

Click of View

@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")

  }))



}

Done with two buttons OK & Cancel

In Swift 4.2 and Xcode 10

Method 1 :

SIMPLE ALERT

let alert = UIAlertController(title: "Your title", message: "Your message", preferredStyle: .alert)



     let ok = UIAlertAction(title: "OK", style: .default, handler: { action in

     })

     alert.addAction(ok)

     let cancel = UIAlertAction(title: "Cancel", style: .default, handler: { action in

     })

     alert.addAction(cancel)

     DispatchQueue.main.async(execute: {

        self.present(alert, animated: true)

})

Method 2 :

ALERT WITH SHARED CLASS

If you want Shared class style(Write once use every where)

import UIKit

class SharedClass: NSObject {//This is shared class

static let sharedInstance = SharedClass()



    //Show alert

    func alert(view: UIViewController, title: String, message: String) {

        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)

        let defaultAction = UIAlertAction(title: "OK", style: .default, handler: { action in

        })

        alert.addAction(defaultAction)

        DispatchQueue.main.async(execute: {

            view.present(alert, animated: true)

        })

    }



    private override init() {

    }

}

Now call alert like this in every ware

SharedClass.SharedInstance.alert(view: self, title: "Your title here", message: "Your message here")

Method 3 :

PRESENT ALERT TOP OF ALL WINDOWS

If you want to present alert on top of all views, use this code

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

    DispatchQueue.main.async(execute: {

        let alertWindow = UIWindow(frame: UIScreen.main.bounds)

        alertWindow.rootViewController = UIViewController()

        alertWindow.windowLevel = UIWindowLevelAlert + 1



        let alert2 = UIAlertController(title: title, message: message, preferredStyle: .alert)

        let defaultAction2 = UIAlertAction(title: "OK", style: .default, handler: { action in

        })

        alert2.addAction(defaultAction2)



        alertWindow.makeKeyAndVisible()



        alertWindow.rootViewController?.present(alert2, animated: true, completion: nil)

    })

}

Function calling

SharedClass.sharedInstance.alertWindow(title:"This your title", message:"This is your message")

Method 4 :

Alert with Extension

extension  UIViewController {



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

        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)

        let ok = UIAlertAction(title: "OK", style: .default, handler: { action in

        })

        let cancel = UIAlertAction(title: "Cancel", style: .default, handler: { action in

        })

        alert.addAction(ok)

        alert.addAction(cancel)

        DispatchQueue.main.async(execute: {

            self.present(alert, animated: true)

        })

    }

}

Now call like this

//Call showAlert function in your class

@IBAction func onClickAlert(_ sender: UIButton) {

    showAlert(withTitle:"Your Title Here", withMessage: "YourCustomMessageHere")

}

Method 5 :

ALERT WITH TEXTFIELDS

If you want to add textfields to alert.

//Global variables

var name:String?

var login:String?



//Call this function like this:  alertWithTF() 

//Add textfields to alert 

func alertWithTF() {



    let alert = UIAlertController(title: "Login", message: "Enter username&password", preferredStyle: .alert)

    // Login button

    let loginAction = UIAlertAction(title: "Login", style: .default, handler: { (action) -> Void in

        // Get TextFields text

        let usernameTxt = alert.textFields![0]

        let passwordTxt = alert.textFields![1]

        //Asign textfileds text to our global varibles

        self.name = usernameTxt.text

        self.login = passwordTxt.text



        print("USERNAME: (self.name!)nPASSWORD: (self.login!)")

    })



    // Cancel button

    let cancel = UIAlertAction(title: "Cancel", style: .destructive, handler: { (action) -> Void in })



    //1 textField for username

    alert.addTextField { (textField: UITextField) in

        textField.placeholder = "Enter username"

        //If required mention keyboard type, delegates, text sixe and font etc...

        //EX:

        textField.keyboardType = .default

    }



    //2nd textField for password

    alert.addTextField { (textField: UITextField) in

        textField.placeholder = "Enter password"

        textField.isSecureTextEntry = true

    }



    // Add actions

    alert.addAction(loginAction)

    alert.addAction(cancel)

    self.present(alert, animated: true, completion: nil)



}

If you're targeting iOS 7 and 8, you need something like this to make sure you're using the right method for each version, because UIAlertView is deprecated in iOS 8, but UIAlertController is not available in iOS 7:

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

    if let getModernAlert: AnyClass = NSClassFromString("UIAlertController") { // iOS 8

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

        myAlert.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))

        self.presentViewController(myAlert, animated: true, completion: nil)

    } else { // iOS 7

        let alert: UIAlertView = UIAlertView()

        alert.delegate = self



        alert.title = title

        alert.message = message

        alert.addButtonWithTitle("OK")



        alert.show()

    }

}

Show UIAlertView in swift language :-

Protocol UIAlertViewDelegate

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

alert.show()

Show UIAlertViewController in swift language :-

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)

Simply do not provide otherButtonTitles in the constructor.

let alertView = UIAlertView(title: "Oops!", message: "Something

happened...", delegate: nil, cancelButtonTitle: "OK")



alertView.show()

But I do agree with Oscar, this class is deprecated in iOS 8, so there won't be no use of UIAlertView if you're doing an iOS 8 only app. Otherwise the code above will work.

With the protocol extensions of Swift 2, you can make a protocol that provides a default implementation to your view controllers:

ShowsAlert.swift

import UIKit



protocol ShowsAlert {}



extension ShowsAlert where Self: UIViewController {

    func showAlert(title: String = "Error", message: String) {

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

        alertController.addAction(UIAlertAction(title: "Ok", style: .Default, handler: nil))

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

    }

}

ViewController.swift

class ViewController: UIViewController, ShowsAlert {

    override func viewDidLoad() {

        super.viewDidLoad()

        showAlert(message: "Hey there, I am an error message!")

    }

}

I found this one,

var alertView = UIAlertView();

alertView.addButtonWithTitle("Ok");

alertView.title = "title";

alertView.message = "message";

alertView.show();

not good though, but it works :)

Update:

but I have found on header file as:

extension UIAlertView {

    convenience init(title: String, message: String, delegate: UIAlertViewDelegate?, cancelButtonTitle: String?, otherButtonTitles firstButtonTitle: String, _ moreButtonTitles: String...)

}

somebody may can explain this.

For SWIFT4, I think, extending UIViewController and creating a reusable confirmation control is the most elegant way.

You can extend the UIViewController as below:

extension UIViewController {



func AskConfirmation (title:String, message:String, completion:@escaping (_ result:Bool) -> Void) {

    let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)

    self.present(alert, animated: true, completion: nil)



    alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: { action in

        completion(true)

    }))



    alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: { action in

        completion(false)

    }))

  }

}

Then you can use it anytime:

 AskConfirmation(title: "YOUR MESSAGE TITLE", message: "YOUR MESSAGE") { (result) in

        if result { //User has clicked on Ok



        } else { //User has clicked on Cancel



        }

    }

    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")

                }

            }

        }

    }

I have another trick. Suppose you have 5 classes where a logout alert to be applied. Try with swift class extension.

File- New- Swift class- Name it.

Add the following:

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)

    }

}

Implement using : self.makeLogOutAlert(). Hope it helps.

I have made a singleton class to make this convenient to use from anywhere in your app: https://github.com/Swinny1989/Swift-Popups

You can then create a popup with multiple buttons like this:

Popups.SharedInstance.ShowAlert(self, title: "Title goes here", message: "Messages goes here", buttons: ["button one" , "button two"]) { (buttonPressed) -> Void in

    if buttonPressed == "button one" { 

      //Code here

    } else if buttonPressed == "button two" {

        // Code here

    }

}

or popups with a single button like this:

Popups.SharedInstance.ShowPopup("Title goes here", message: "Message goes here.")

Swift 3

The following is a simple example of how to create a simple alert with one button with Swift 3.

let alert = UIAlertController(title: "Title",

                              message: "Message",

                              preferredStyle: .alert)

alert.addAction(UIAlertAction(title: "Ok", style: .default))

present(alert, animated: true)

In the above example the handle callback of the action has been omitted because the default behaviour of an alert view with one button is to disappear when the button is clicked.

Here is how to create another action, which could be added to the alert with "alert.addAction(action)". The different styles are .default, .destructive and .cancel.

let action = UIAlertAction(title: "Ok", style: .default) { action in

    // Handle when button is clicked    

}

I got the following UIAlertView initialization code to compile without errors (I thing the last, varyadic part is tricky perhaps). But I had to make sure the class of self (which I am passing as the delegate) was adopting the UIAlertViewDelegate protocol for the compile errors to go away:

let alertView = UIAlertView(

                  title: "My Title",

                  message: "My Message",

                  delegate: self,

                  cancelButtonTitle: "Cancel",

                  otherButtonTitles: "OK"

                )

By the way, this is the error I was getting (as of Xcode 6.4):

Cannot find an initializer for type 'UIAlertView' that accepts an
argument list of type '(title: String, message: String, delegate:
MyViewController, cancelButtonTitle: String, otherButtonTitles:
String)'

As others mentioned, you should migrate to UIAlertController if you can target iOS 8.x+. To support iOS 7, use the code above (iOS 6 is not supported by Swift).

The reason it doesn't work because some value you passed to the function isn't correct. swift doesn't like Objective-C, you can put nil to arguments which are class type without any restriction(might be). Argument otherButtonTitles is defined as non-optional which its type do not have (?)at its end. so you must pass a concrete value to it.

@IBAction func Alert(sender: UIButton) {



    var alertView:UIAlertView = UIAlertView()

    alertView.title = "Alert!"

    alertView.message = "Message"

    alertView.delegate = self

    alertView.addButtonWithTitle("OK")



    alertView.show()



}

Try this

Use this code to display an alertview

  let alertController = UIAlertController(title: "Hello  Coders", message: "your alert message", preferredStyle: .Alert)

        let defaultAction = UIAlertAction(title: "Close Alert", style: .Default, handler: nil)

        alertController.addAction(defaultAction)



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

Reference: Swift Show Alert using UIAlertController

in xcode 9

let alert = UIAlertController(title: "Alert", message: "message", preferredStyle: UIAlertControllerStyle.alert)

alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.default, handler: nil))

self.present(alert, animated: true, completion: nil)

 let alertController = UIAlertController(title: "Select Photo", message: "Select atleast one photo", preferredStyle: .alert)

    let action1 = UIAlertAction(title: "From Photo", style: .default) { (action) in

        print("Default is pressed.....")

    }

    let action2 = UIAlertAction(title: "Cancel", style: .cancel) { (action) in

        print("Cancel is pressed......")

    }

    let action3 = UIAlertAction(title: "Click new", style: .default) { (action) in

        print("Destructive is pressed....")



    }

    alertController.addAction(action1)

    alertController.addAction(action2)

    alertController.addAction(action3)

    self.present(alertController, animated: true, completion: nil)



}

SWIFT 4 : Simply create a extension to UIViewController as follows:

extension  UIViewController {        

    func showSuccessAlert(withTitle title: String, andMessage message:String) {

        let alert = UIAlertController(title: title, message: message,

                                  preferredStyle: UIAlertController.Style.alert)

        alert.addAction(UIAlertAction(title: "OK".localized, style:

        UIAlertAction.Style.default, handler: nil))

        self.present(alert, animated: true, completion: nil)

    }

}

Now in your ViewController, directly call above function as if they are provided by UIViewController.

    yourViewController.showSuccessAlert(withTitle: 

      "YourTitle", andMessage: "YourCustomTitle")

try This.
Put Bellow Code In Button.

let alert = UIAlertController(title: "Your_Title_Text", message: "Your_MSG", preferredStyle: UIAlertControllerStyle.alert)

alert.addAction(UIAlertAction(title: "Your_Text", style: UIAlertActionStyle.default, handler: nil))

self.present(alert, animated:true, completion: nil)

SWIFT 4.X

    let alert = UIAlertController(title: "user entered title", message: "user entered message", preferredStyle: .alert)

    alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { action in

        print("Okay'd")

    }))

    alert.addAction(UIAlertAction(title: "Cancel", style: .default, handler: { action in

        print("cancelled")

    }))

    self.present(alert, animated: true, completion: nil)

Here is a funny example in Swift:

private func presentRandomJoke() {

  if let randomJoke: String = jokesController.randomJoke() {

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

    alertController.addAction(UIAlertAction(title:"Done", style:UIAlertActionStyle.Default, handler:nil))

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

  }

}

Here is a pretty simple function of AlertView in Swift :

class func globalAlertYesNo(msg: String) {

        let alertView = UNAlertView(title: "Title", message: msg)



        alertView.messageAlignment = NSTextAlignment.Center

        alertView.buttonAlignment  = UNButtonAlignment.Horizontal



        alertView.addButton("Yes", action: {



            print("Yes action")



        })



        alertView.addButton("No", action: {



            print("No action")



        })



        alertView.show()



    }

You have to pass message as a String where you use this function.

The Old Way: UIAlertView

let alertView = UIAlertView(title: "Default Style", message: "A standard alert.", delegate: self, cancelButtonTitle: "Cancel", otherButtonTitles: "OK")

alertView.alertViewStyle = .Default

alertView.show()



// MARK: UIAlertViewDelegate



 func alertView(alertView: UIAlertView, clickedButtonAtIndex buttonIndex: Int) {

 switch buttonIndex {



    // ...

   }

  }

The New Way: UIAlertController

let alertController = UIAlertController(title: "Default Style", message: "A standard alert.", preferredStyle: .Alert)



let cancelAction = UIAlertAction(title: "Cancel", style: .Cancel) { (action) in

// ...

 }

 alertController.addAction(cancelAction)



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

// ...

 }

 alertController.addAction(OKAction)

 self.presentViewController(alertController, animated: true) {

 // ...

}

on IOS 9, you can do this

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)

// Generic Class For UIAlertView

//MARK:- MODULES

import Foundation

import UIKit



//MARK:- CLASS

class Alert  : NSObject{



static let shared = Alert()



var okAction : AlertSuccess?

typealias AlertSuccess = (()->())?

var alert: UIAlertController?



/** show */

public func show(title : String?, message : String?, viewController : UIViewController?, okAction : AlertSuccess = nil) {



    let version : NSString = UIDevice.current.systemVersion as NSString

    if  version.doubleValue >= 8 {

        alert = UIAlertController(title: title, message: message, preferredStyle:.alert)

        alert?.addAction(UIAlertAction(title: "OK", style: .default, handler: { (action: UIAlertAction) in



            if let okAction = okAction {

                okAction()

            }

        }))

        viewController?.present(alert ?? UIAlertController(), animated:true, completion:nil);

    }

}



/** showWithCancelAndOk */

public func showWithCancelAndOk(title : String, okTitle : String, cancelTitle : String, message : String, viewController : UIViewController?, okAction : AlertSuccess = nil, cancelAction : AlertSuccess = nil) {

    let version:NSString = UIDevice.current.systemVersion as NSString;



    if  version.doubleValue >= 8 {

        alert = UIAlertController(title: title, message: message, preferredStyle:.alert)



        alert?.addAction(UIAlertAction(title: cancelTitle, style: .default, handler: { (action: UIAlertAction) in



            if let cancelAction = cancelAction {

                cancelAction()

            }

        }))

        alert?.addAction(UIAlertAction(title: okTitle, style: .default, handler: { (action: UIAlertAction) in



            if let okAction = okAction {

                okAction()

            }

        }))

        viewController?.present(alert!, animated:true, completion:nil);

    }

}



/** showWithTimer */

public func showWithTimer(message : String?, viewController : UIViewController?) {



    let version : NSString = UIDevice.current.systemVersion as NSString

    if  version.doubleValue >= 8 {

        alert = UIAlertController(title: "", message: message, preferredStyle:.alert)

        viewController?.present(alert ?? UIAlertController(), animated:true, completion:nil)

        let when = DispatchTime.now() + 1

        DispatchQueue.main.asyncAfter(deadline: when){

            self.alert?.dismiss(animated: true, completion: nil)

        }

    }

}

}

Use:-

Alert.shared.show(title: "No Internet Connection", message: "The internet connection appers to be offline.", viewController: self) //without ok action



Alert.shared.show(title: "No Internet Connection", message: "The internet connection appers to be offline.", viewController: self, okAction: {

                            //ok action

                        }) // with ok action



Alert.shared.show(title: "No Internet Connection", message: "The internet connection appers to be offline.", viewController: self, okAction: {

                            //ok action 

}, cancelAction: {

 //cancel action

}) //with cancel and ok action



Alert.shared.showWithTimer(message : "This is an alert with timer", viewController : self) //with timer

  // 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()