Added programmatically UITabBarItem after switching app got crashed-CodePudding

For existing UITabBarController already in storyboard do have Two TabBars (Home / Settings).

Now I added two more TabBarIems based on conditions based (programVC / reportVC) i.e., UIViewController.

When Switching Tab programVC or reportVC app get crashed.

The @IBOutlet var skeletonView: UIView! added in ProgramReportVC set to nil

class MainTabbarController: UITabBarController {

    override func viewDidLoad() {
        super.viewDidLoad()
        addedConditionalTabs(isInserted: true)      
    }

// For existing tab inserted new tabs based on condition
func addedConditionalTabs(isInserted: Bool){
    if isInserted{
        let programVC = ProgramReportVC() // ProgramReportVC -> UIViewController
       programVC = “Program”
        let reportVC = ProgramReportVC()
       reportVC.screenTitle = “Report”

       programVC.tabBarItem = UITabBarItem(title: "Program", image: UIImage(named: “ProgramImage”), tag: 2)
       reportVC.tabBarItem = UITabBarItem(title: "Report", image: UIImage(named: “ReportImage”), tag: 3)

        self.viewControllers?.insert(programVC, at: 2)
        self.viewControllers?.insert(reportVC, at: 3)
    }

 }

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

How to resolved Unexpectedly found nil ?

programVC ->

@IBOutlet var skeletonView: UIView!
@IBOutlet var views: [UIView]!
@IBOutlet var subviews: [UIView]!


override func viewDidLoad() {
    super.viewDidLoad()
    self.showSkeleton()
  }


func showSkeleton() {
    self.skeletonView.frame = CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)
    self.view.addSubview(self.skeletonView)
    self.view.bringSubviewToFront(self.skeletonView)
    let gradient = SkeletonGradient(baseColor: UIColor(named: "skeletonColor")!)
    let animation = SkeletonAnimationBuilder().makeSlidingAnimation(withDirection: .leftRight)
    self.skeletonView.isSkeletonable = true
    for items in views {
        items.isSkeletonable = true
    }
    for items in subviews {
        items.isSkeletonable = true
        items.showAnimatedGradientSkeleton(usingGradient: gradient, animation: animation)
    }
}

CodePudding user response：

It sounds like this is unrelated to the UITabBarController or how you're adding VCs to it. If a UIView that is nil gets force unwrapped (as is the case with your skeletonView IBOutlet), that will cause a crash regardless of whether the VC is presented by a tab controller or by something else.

Update: Based on the thread conversation, your issue is that you're accessing skeletonView inside of the ProgramReportVC's viewDidLoad method. The VC's view will not have been initialized at that point in time, which also means its IBOutlets will not have been resolved yet.

My recommendation would be to call showSkeleton() in viewDidAppear instead, since UI updates in general are best done once the UI is actually visible on the screen.

CodePudding user response：

if let programReportVC = UIStoryboard.identifier(.Dashboard).instantiateViewController(identifier: "ProgramReportVC") as? ProgramReportVC{
    // Do your Stuff here.
}

It's worked if added via like this.