Cwa-app-android: Simplify Fragments view unbinding code

[henriquenfaria]

Avoid duplicates

• [x] This enhancement request has not already been raised before
• [x] Enhancement request is specific for Android only, for general issues / questions that apply to iOS and Android please raise them in CWA-Wishlist
• [x] If you are proposing a new feature, please do so in CWA-Wishlist

Current Implementation

The View Binding usage inside the app's Fragments is a bit complicated and repetitive.

1. duplicated binding properties to be able to get rid of the null checks:

private var _binding: FragmentMainBinding? = null
private val binding: FragmentMainBinding get() = _binding!!

1. duplicated code, every Fragment override onDestroyView in order to unbind the view:

override fun onDestroyView() {  
     super.onDestroyView()  
    _binding = null 
}

Suggested Enhancement

My suggestion is to create a lifecycle-aware delegated property that automatically unbinds the view during onDestroyView. As a nice side-effect, we would be able to remove the _binding property.

The implementation would be similar to https://proandroiddev.com/make-android-view-binding-great-with-kotlin-b71dd9c87719

Expected Benefits

• The code would become simpler and cleaner.
• Less duplicated code.
• Less chance of Fragment memory leaks caused by missing _binding = null statements.

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Internal Tracking ID: EXPOSUREAPP-1926

[henriquenfaria]

Pull Request: https://github.com/corona-warn-app/cwa-app-android/pull/928

[henriquenfaria]

Hi @pwoessner
Any updates from your side regarding this issue/pr?

[svengabr]

Hey @henriquenfaria sorry for the late response here. We are currently working hard on finalizing the next release. I have re-assigned the issue to make sure it gets in the hand of the right people soon.

Best regards,
SG

Corona-Warn-App Open Source Team

[henriquenfaria]

No problem @svengabr :)
Let me know if you need my help to rebase/update my PR.