CollectionView `DidSelect` method is being called but not pushing the next VC, how to fix it?

Question

I am trying to push another VC from UICollectionView DidSelect delegate, it is being called, but oddly, it is not pushing the initiated VC, how can i fix it?

my AppDelegate.swift looks like this:

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?
    weak var coordinator: MainCoordinator?
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        self.window = UIWindow(frame: UIScreen.main.bounds)
        coordinator = MainCoordinator(navigationController: UINavigationController())
        self.window?.rootViewController = UIStoryboard.splashViewController()
        self.window?.makeKeyAndVisible()
        return true
    }

}

and my SplashViewController , where I switch the RootVC to MainVC in DispatchQueue after the SplashViewController completed:

class SplashViewController: UIViewController {
    
    weak var coordinator: MainCoordinator?
    
    //MARK: -viewDidLoad()
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Do any additional setup after loading the view.
    }
    // MARK: - viewDidAppear()
    override func viewDidAppear(_ animated: Bool) {
        let animationView = AnimationView()
        let animation = Animation.named("SplashAnimation", bundle: Bundle.main)
        animationView.animation = animation
        animationView.frame = CGRect(origin: .zero, size: CGSize(width: self.view.frame.size.width, height: 200))
        animationView.center = self.view.center
        animationView.loopMode = .playOnce
        animationView.contentMode = .scaleAspectFit
        animationView.play { (finished) in
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.5, execute: {
                if let vc = self.storyboard?.instantiateViewController(identifier: "MainViewController") as? MainViewController {
                    self.view.window?.rootViewController = vc
                    self.view.window?.makeKeyAndVisible()
                }
                
            })
        }
        view.addSubview(animationView)
    }
}

and in my UICollectionView 's DidSelect delegate, I am doing this:

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        if collectionView == categoryCollectionView {
            let vc = self.storyboard?.instantiateViewController(identifier: "SymptomViewController") as! SymptomViewController
            self.navigationController?.pushViewController(vc, animated: true)
        } else {
            print("next collectionView not ready yet.. .")
        }
    }

which usually runs expected, but now it is printing the print statement but never pushing the next VC.. .

Answer 1

First of all, you need to make sure that if collectionView == categoryCollectionView really equals true.

Second, I noticed that your MainViewController doesn't seem to be embedded in a NavigationController , so when you call self.navigationController?.pushViewController(vc, animated: true) , it's possibly going to do nothing as the optional chaining will detect that self.navigationController is nil .

Answer 2

Due to my low reputation I cannot add this as a comment, therefore I am posting it in this way.

Have you tried placing a breakpoint on the first line of the collectionView delegate method and checking the collectionView with "po" command in debugger? Since your if statement fails, most probably it is some other collectionView triggering this delegate method. You have to make sure that if collectionView == categoryCollectionView truly returns true.

Also, once app execution is halted on the breakpoint, it is often very useful to check the debug navigator (in case you haven't yet) and get to know what lead to the specified breakpoint.