TransitionController - Initial RootViewController view lifecycle not occuring

[markst]

The initial root view controller view lifecycle functions are not being called on initial load of root view controller. All subsequent lifecycle functions are working as expect.

[markst]

This is due to shouldAutomaticallyForwardAppearanceMethods being implemented & not calling the appropriate appearance transition functions on initial setup of root view controller:

#938 (comment)

[markst]

There needs to be a feature where by lifecycle functions are performed when updating root view controller directly.

self.rootViewController = UIViewController() // View lifecycle not called
self.transition(to: UIViewController(), completion: nil) // View lifecycle called

[daniel-jonathan]

I see what you are describing. I have an idea of how to make it work correctly. I will give it a try after another task I am working on.

[markst]

Not a huge fan of it, but passing the transition logic on as follows, resolved it for me:

open class TransitionController: UIViewController {

    open override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        self.rootViewController.beginAppearanceTransition(true, animated: animated)
    }
    
    open override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        self.rootViewController.endAppearanceTransition()
    }
    
    open override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        self.rootViewController.beginAppearanceTransition(false, animated: animated)
    }
    
    open override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        self.rootViewController.endAppearanceTransition()
    }

[daniel-jonathan]

Well I was thinking that in the shouldAutomaticallyForwardAppearanceMethods call, we can return true on the first instance.

[markst]

yeah sounds fine. trusting it's toggled at the right occasion

[daniel-jonathan]

I actually like your solution better as it is clear as to what is happening. With a hidden flag, which I am not a fan of, does not demonstrate clarity when looking through the code. I am going to test how your solution works.

[daniel-jonathan]

This is the corresponding commit that will be in the next release 5e8497d, thank you!

[daniel-jonathan]

Please find this fix in Material 2.12.8 :)