Displaying a UIAlertController in GameScene (SpriteKit/Swift)

Question

The simple way to display a UIAlertView, in swift is:

let alert = UIAlertView()
alert.title = \"Alert!\"
alert.message = \"A wise message\"
alert.addButtonWi         


        

Answer 1

There are many ways to handle this situation, I do not recommend Jozemite Apps answer, because this will cause problems on apps with more than 1 view controller.(you want to present the alert on the current view controller, not the root)

My preferred way of doing it is through delegation. What needs to be done is create a protocol to handle messaging:

import Foundation
protocol ViewControllerDelegate
{
    func sendMessage(message:String);
}

In your view controller:

class ViewController : UIViewController, ViewControllerDelegate
{
    ...
    func sendMessage(message:String)
    {
       //do alert view code here
    }

    //in the view controllers view did load event
    func viewDidLoad()
    {
        var view = self.view as! GameSceneView
        view.delegate = self
    }

In your view code:

  var delegate : ViewControllerDelegate

Finally in game scene where you want to present:

self.view.delegate?.sendMessage(message)

This way allows limited access to the VC, and can be modified with more options when needed.

Another way is to set up a notification system, and use NSNotificationCenter to pass a message from the scene to the current VC and have it send a message;

in ViewController

func viewDidLoad()
{
  NSNotificationCenter.defaultCenter().addObserver(self,selector:"AlertMessage:",name:"AlertMessage",object:nil);

}

func AlertMessage(notification:NSNotification)
{
    if(let userInfo = notification.userInfo)
    {
      let message = userInfo["message"]
      ....//do alert view call here
    }
}

In Game scene code:

...at the spot you want to send a message
let userInfo = ["message":message];
NSNotificationCenter.defaultCenter.postNotificationNamed("AlertMessage",object:nil,userInfo:userInfo)

Another approach is to save the view controller pointer to game scene view:

//in Game Scene View code
var viewController : UIViewController; 

//in the view controllers view did load event
func viewDidLoad()
{
    var view = self.view as! GameSceneView
    view.viewController = self
}

//finally in game scene where you want to present
let myAlert: UIAlertController = UIAlertController(title: "Alert!", message: "Oh! Fancy", preferredStyle: .Alert)
myAlert.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
self.view.viewController.presentViewController(myAlert, animated: true, completion: nil)

Yet another way is to make your view controller global.

In view controller code: private var _instance : UIViewController

class ViewController : UIViewController
{
    class var instance
    {
        get
        {
            return _instance;
        }
    }

    func viewDidLoad()
    {
       _instance = self;
    }
}

Then just call

ViewController.instance!.  

whenever you need access to your view controller.

Each of these methods have there strengths and weaknesses, so choose whatever way works best for you.