Swift - launch-screen SIGABRT error

Question

just a real quick issue i'm having with my current swift project. Essentially; i'm trying to implement a combination of tutorials to present an animated launch screen for my application; but with the following code I'm getting an error "Thread 1: signal SIGABRT" which I can't seem to figure out the root cause for. The example project I was following was using a tableview as there main home screen with is the only difference between our projects; but I can't find aa justification in the code that would be responsible for proving my errors. The error resides somewhere within the following as my the remainder of my viewController's have been left blank to try and find the root of the problem.

Here's my app delegate file where the error resides import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


        func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
            // Override point for customization after application launch.

            self.window = UIWindow(frame: UIScreen.main.bounds)
            self.window!.backgroundColor = UIColor(red: 241/255, green: 196/255, blue: 15/255, alpha: 1)
            self.window!.makeKeyAndVisible()

            // rootViewController from StoryBoard
            let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
            let navigationController = mainStoryboard.instantiateViewController(withIdentifier: "navigationController")
            self.window!.rootViewController = navigationController

            // logo mask
            navigationController.view.layer.mask = CALayer()
            navigationController.view.layer.mask!.contents = UIImage(named: "logo.png")!.cgImage
            navigationController.view.layer.mask!.bounds = CGRect(x: 0, y: 0, width: 60, height: 60)
            navigationController.view.layer.mask!.anchorPoint = CGPoint(x: 0.5, y: 0.5)
            navigationController.view.layer.mask!.position = CGPoint(x: navigationController.view.frame.width / 2, y: navigationController.view.frame.height / 2)

            // logo mask background view
            let maskBgView = UIView(frame: navigationController.view.frame)
            maskBgView.backgroundColor = UIColor.white
            navigationController.view.addSubview(maskBgView)
            navigationController.view.bringSubview(toFront: maskBgView)

            // logo mask animation
            let transformAnimation = CAKeyframeAnimation(keyPath: "bounds")
            transformAnimation.delegate = self as? CAAnimationDelegate
            transformAnimation.duration = 1
            transformAnimation.beginTime = CACurrentMediaTime() + 1 //add delay of 1 second
            let initalBounds = NSValue(cgRect: (navigationController.view.layer.mask!.bounds))
            let secondBounds = NSValue(cgRect: CGRect(x: 0, y: 0, width: 50, height: 50))
            let finalBounds = NSValue(cgRect: CGRect(x: 0, y: 0, width: 2000, height: 2000))
            transformAnimation.values = [initalBounds, secondBounds, finalBounds]
            transformAnimation.keyTimes = [0, 0.5, 1]
            transformAnimation.timingFunctions = [CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut), CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)]
            transformAnimation.isRemovedOnCompletion = false
            transformAnimation.fillMode = kCAFillModeForwards
            navigationController.view.layer.mask!.add(transformAnimation, forKey: "maskAnimation")

            // logo mask background view animation
            UIView.animate(withDuration: 0.1,
                           delay: 1.35,
                           options: UIViewAnimationOptions.curveEaseIn,
                           animations: {
                            maskBgView.alpha = 0.0
            },
                           completion: { finished in
                            maskBgView.removeFromSuperview()
            })

            // root view animation
            UIView.animate(withDuration: 0.25,
                           delay: 1.3,
                           options: UIViewAnimationOptions(),
                           animations: {
                            self.window!.rootViewController!.view.transform = CGAffineTransform(scaleX: 1.05, y: 1.05)
            },
                           completion: { finished in
                            UIView.animate(withDuration: 0.3,
                                           delay: 0.0,
                                           options: UIViewAnimationOptions(),
                                           animations: {
                                            self.window!.rootViewController!.view.transform = CGAffineTransform.identity
                            },
                                           completion: nil
                            )
            })

            return true

    }



    func applicationWillResignActive(_ application: UIApplication) {
        // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
        // Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
    }

    func applicationDidEnterBackground(_ application: UIApplication) {
        // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
        // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
    }

    func applicationWillEnterForeground(_ application: UIApplication) {
        // Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
    }

    func applicationDidBecomeActive(_ application: UIApplication) {
        // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
    }

    func applicationWillTerminate(_ application: UIApplication) {
        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    }


}

Answer 1

There are two places where your application might crash.

The first crash possibility is related to instantiating UIViewController from Storyboard . Instead of instantiating from Storyboard you can try some blank UIViewController :

let navigationController = UIViewController()
self.window!.rootViewController = navigationController

If it doesn't crash then there are some issues with your Main.storyboard .

The second place that might cause a crash:

navigationController.view.layer.mask!.contents = UIImage(named: "logo.png")!.cgImage

Please make sure that your image is fine and it exists in the project.

Also, you might want to rethink you approach to optional values unwrapping. Use:

navigationController.view.layer.mask?.contents = UIImage(named: "logo.png")?.cgImage

Instead of:

navigationController.view.layer.mask!.contents = UIImage(named: "logo.png")!.cgImage

Edit:

I have caught your exception:

'NSInvalidArgumentException', reason: 'Storyboard () doesn't contain a view controller with identifier 'navigationController''

Please make sure you have a Storyboard ID correctly specified for your navigationController .

If you need a hint how to catch exceptions, ask in comments.