Swift Switching To and FromTable ViewController Issue Using Custom Segue - ios

Question

I have run into an issue when using a custom segue. I have two tableviews that I'm an trying to switch back and forth from. When I click on a cell in tableview1 it should take me to tableview2. I have a button on tableview2 that connects to the exit of the storyboard. From there it should take me back to tableview1 but whenever I press the button, the application crashes with a BAD_ACCESS error.
Here is my custom segue class:
class TableViewSegue: UIStoryboardSegue {
override func perform() {
scale()
}
func scale () {
let toViewcontroller = self.destination
let fromViewcontroller = self.source
let containerView = fromViewcontroller.view.superview
let originalCenter = fromViewcontroller.view.center
toViewcontroller.view.transform = CGAffineTransform(scaleX: 0.05, y: 0.05)
toViewcontroller.view.center = originalCenter
containerView?.addSubview(toViewcontroller.view)
UIView.animate(withDuration: 0.5, delay: 0, options: .curveEaseInOut, animations: {
toViewcontroller.view.transform = CGAffineTransform.identity
}, completion: { success in
fromViewcontroller.present(toViewcontroller, animated: false, completion: nil) //The application crashes and highlights this line as the error.
})
}
}
I have implemented this method in my tableViewController1:
#IBAction func prepareForUnwind(segue: UIStoryboardSegue) {
}
Not sure why the tableview2 does not dismiss.
EDIT: The issue had to do with needing a navigation controller.

Answer 1

The problem is that you are presenting the toViewcontroller each time a segue is performed. So the app presents table2 over table1, and then tries again to present table1 over table2 on the unwind.
Modify your custom segue to check - essentially - which direction you're going:
class TableViewSegue: UIStoryboardSegue {
override func perform() {
scale()
}
func scale () {
let toViewcontroller = self.destination
let fromViewcontroller = self.source
let containerView = fromViewcontroller.view.superview
let originalCenter = fromViewcontroller.view.center
toViewcontroller.view.transform = CGAffineTransform(scaleX: 0.05, y: 0.05)
toViewcontroller.view.center = originalCenter
containerView?.addSubview(toViewcontroller.view)
let fromP = fromViewcontroller.presentingViewController
UIView.animate(withDuration: 0.5, delay: 0, options: .curveEaseInOut, animations: {
toViewcontroller.view.transform = CGAffineTransform.identity
}, completion: { success in
// if nil, we are presenting a new VC
if fromP == nil {
fromViewcontroller.present(toViewcontroller, animated: false, completion: nil)
} else {
fromViewcontroller.dismiss(animated: false, completion: nil)
}
})
}
}
Note: This is assuming:
you are not trying to push/pop within a UINavigationController ... you'd need to add some other checks to handle that.
you are only going one-level-in, that is, you are not presenting, presenting, presenting, etc. and then trying to unwind.