Swift custom segue doesn't work on consecutive segues - ios

Question

I made a custom segue that moves the current view to the left and moves the next view in from the right at the same time. When I used it on the first segueway it works perfectly, but when used in the next segueway only the destination view moves. The code for the segue looks like the following:
class CustomSlideSegue: UIStoryboardSegue {
override func perform() {
let firstVCView = self.sourceViewController.view as UIView!
let secondVCView = self.destinationViewController.view as UIView!
let screenWidth = UIScreen.mainScreen().bounds.size.width
let screenHeight = UIScreen.mainScreen().bounds.size.height
secondVCView.frame = CGRectMake(screenWidth, 0, screenWidth, screenHeight)
let window = UIApplication.sharedApplication().keyWindow
window?.insertSubview(secondVCView, aboveSubview: firstVCView)
UIView.animateWithDuration(0.6, animations: { () -> Void in
firstVCView.transform = CGAffineTransformMakeTranslation(-screenWidth, 0)
secondVCView.transform = CGAffineTransformMakeTranslation(-screenWidth, 0)
}) { (Finished) -> Void in
self.sourceViewController.presentViewController(self.destinationViewController as UIViewController, animated: false, completion: nil)
}
}
}
And here is the code from the view controller button action method where I start the segue:
performSegueWithIdentifier("customSlideSegue", sender: self)
Here is a video showing the segues:
Can anyone see the problem? Or how should I go about debugging this? Thankful for replies!

Answer 1

the problem was that the second time you call the segue the sourceviewcontroller's view's transform already has a value of -screenWidth and thus it doesn't get pushed out of the screen. change your code to the following:
override func perform() {
let firstVCView = self.sourceViewController.view as UIView!
let secondVCView = self.destinationViewController.view as UIView!
let screenWidth = UIScreen.mainScreen().bounds.size.width
secondVCView.transform = CGAffineTransformMakeTranslation(screenWidth, 0)
let window = UIApplication.sharedApplication().keyWindow
window?.insertSubview(secondVCView, aboveSubview: firstVCView)
UIView.animateWithDuration(0.6, animations: { () -> Void in
firstVCView.transform = CGAffineTransformMakeTranslation(-screenWidth, 0)
secondVCView.transform = CGAffineTransformIdentity
}) { (Finished) -> Void in
self.sourceViewController.presentViewController(self.destinationViewController, animated: false, completion: nil)
}
}