Instantiating Initial View Controller Provides Nil

Question

For my tab bar controller, I want a transition for 4/5 tabs. The fifth tab i was able to successfully perform a different transition, but trying to add it to the other view controllers caused a crash.

Action Storyboard: This storyboard contains my tab bar controller, and my camera view controller. The transition for this view controller is the only one that works. When i try to transition different tabs that are not in the tab bar controllers storyboard, it crashes

This is the storyboard with the problem

For example, I want to provide a different transition for the view controller in this storyboard. However, i get the error: Unexpectedly found nil while unwrapping an optional value

This is my code:

func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool { if let restoreID = viewController.restorationIdentifier { if restoreID == "NavigationCamera" { // This is the transition that works if let nav = tabBarController.viewControllers![tabBarController.selectedIndex] as? UINavigationController { print("Nav is allowed") let newVC = tabBarController.storyboard?.instantiateViewController(withIdentifier: "CameraView") let transition = CATransition() transition.duration = 0.25 transition.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut) transition.type = kCATransitionPush transition.subtype = kCATransitionFromTop nav.view.layer.add(transition, forKey: nil) nav.pushViewController(newVC!, animated: false) return false } } else { if let otherNav = tabBarController.viewControllers![tabBarController.selectedIndex] as? UINavigationController { print("Other nav is allowed") let vcID = restoreID + "View" print(vcID) let myVC = otherNav.storyboard?.instantiateInitialViewController() let otherTransition = CATransition() otherTransition.duration = 0.25 otherTransition.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut) otherTransition.type = kCATransitionPush otherTransition.subtype = kCATransitionFade otherNav.view.layer.add(otherTransition, forKey: nil) // This is where the error occurs and crashes otherNav.pushViewController(myVC!, animated: false) return false } } } return true }

Once again the error i get is:

Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value

otherNav.storyboard?.instantiateInitialViewController() is returning nil and then you are using myVC! on nil value — Tomasz Czyżak
– Tomasz Czyżak, Commented Dec 1, 2017 at 7:16
I was having the same issue - turns out I didn't have a link to a Controller - followed the steps here: stackoverflow.com/questions/26311000/… — Hayden Crocker
– Hayden Crocker, Commented Jul 16, 2018 at 12:49

Tomasz Czyżak · Accepted Answer · 2017-12-01 07:18:58Z

3

let storyboard = UIStoryboard(name: <other storyboard>, bundle: nil) let myVC = storyboard.instantiateViewController(withIdentifier: <your navigation controler>)

answered Dec 1, 2017 at 7:18

Tomasz Czyżak

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2 Comments

vApp Over a year ago

is the <other storyboard> the name of my storyboard file? e.g. "Home.storyboard"

Tomasz Czyżak Over a year ago

without extension for example: let storyboard = UIStoryboard(name: "Main", bundle: nil)

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