IssueTracker

With the removal of this what is the proper and easy way to know when the view is actually attached to parent?

Going edge to edge with BottomSheetDialogFragment force us to get the view parents to disable fitsSystemWindows and handling this properly.

Unfortunately the view is not yet attached during the call to onViewCreated and onActivityCreated is the best place.

From your initial post I suppose onViewStateRestored is the new proper callback, but the name is counter intuitive and I initially thought that this would not have been called on first creation as nothing to restore.

Re #8 - onActivityCreated() runs literally back to back with onViewCreated(), so the state you're in would be exactly the same between the two calls.

We've been meaning to make it more consistent whether you're attached or not in onViewCreated() for a while here (as it turns out right now you could be in either case), I've created b/149024125 to track getting that fixed.

It seems the new beta tracker does not automatically watch issues on comment did not receive this answer :(.

Anyway with Fragment 1.2.1 in BottomSheetDialogFragment this is not the case.

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        logError("TAG") { "onActivityCreated: ${view?.parent?.parent?.parent}" }
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        logError("TAG") { "onViewCreated: ${this.view?.parent?.parent?.parent}" }
        logError("TAG") { "onViewCreated: ${view.parent?.parent?.parent}" }
    }

    override fun onViewStateRestored(savedInstanceState: Bundle?) {
        super.onViewStateRestored(savedInstanceState)
        logError("TAG") { "onViewStateRestored: ${this.view?.parent?.parent?.parent}" }
    }

Always and consistently gives:

2020-02-10 18:48:24.498 31061-31130/XXX E/TAG: BaseBottomSheetDialogFragment.onViewCreated@63: onViewCreated: null
2020-02-10 18:48:24.499 31061-31130/XXX E/TAG: BaseBottomSheetDialogFragment.onViewCreated@64: onViewCreated: null
2020-02-10 18:48:24.519 31061-31129/XXX E/TAG: BaseBottomSheetDialogFragment.onActivityCreated@58: onActivityCreated: android.widget.FrameLayout{f46459f V.E...... ......I. 0,0-0,0 #7f0a0137 app:id/container}
2020-02-10 18:48:24.520 31061-31129/XXX E/TAG: BaseBottomSheetDialogFragment.onViewStateRestored@70: onViewStateRestored: android.widget.FrameLayout{f46459f V.E...... ......I. 0,0-0,0 #7f0a0137 app:id/container}

So Ian the issue is about DialogFragment:

https://cs.android.com/androidx/platform/frameworks/support/+/androidx-master-dev:fragment/fragment/src/main/java/androidx/fragment/app/DialogFragment.java;l=488

Seems this is also not changed in your 1.3.0 commit listed here, would be nice that it is and that onViewCreated works in that case too if possible or find a proper common ways that works for all cases.

Work hasn't completed on this bug (which is why it isn't marked as 'Fixed') - DialogFragment is one of the things we're still looking at.

Was just commenting about the fact that those 2 events are not the same for dialog fragment despite the link you gave.

Since I'm rewriting a lot of stuff, I wonder what will be the final target for 1.3?

• onViewCreated will be attached for every cases
• onViewStateRestored will be attached for every cases
• This is still not determined and maybe not done for 1.3 so I should not bother yet.

This bug is solely about onActivityCreated. If you want to talk about onViewCreated, let's move the conversation onto that bug, linked in comment#9.

If you want a foolproof signal for the View being attached, you should look at the View layer and doOnAttach from core-ktx. You don't need anything at the Fragment layer.

I think there's a communication issue here :) My issue is about onActivityCreated I don't care what is the replacement I just need to know what it will be :)

You tell me that onActivityCreated and onViewCreated are the same as called side by side, this is as proven unfortunately not true for dialog fragments that are fragments.

onActivityCreated is the only callback that is made after the view is properly attached and things are all tied up.

Since you deprecate onActivityCreated my question is unchanged what is / will be the proper callback for dialog fragment that ensure the same state as currently.

I think the main communication issue is that I'm talking about the View moving to the attached state and you're talking about when the view has been added to its parent ViewGroup. While related (a View cannot be attached unless it is added to a ViewGroup that is attached), they are absolutely not the same thing.

For a non-dialog Fragment, the View is added to its container (but not always attached) right before onViewCreated() is called. The other bug is about ensuring that it is both added and attached before running onViewCreated().

For a dialog Fragment, there is no container. FragmentManager does nothing before onViewCreated(). This is likely to continue to be the case in Fragment 1.3.0 and beyond. DialogFragment currently adds the View to the dialog in onActivityCreated(), but still does not wait for the View to be attached. We'll need to continue to do that for backward compatibility, but will rewrite DialogFragment to allow for an eventual removal of onActivityCreated() entirely. That's the work I mentioned in #12.

Like I mentioned, you should really use doOnAttach in onCreateView or onViewCreated if you want to get a callback for when your View has been attached and, by prerequisite, added to its parent. That will work consistently across all cases, Fragment, DialogFragment, or non-Fragment use cases.

Thanks for clarification effectively I had no idea about added to parent being different from attached at the view level. Is there some doc page outside of raw API description that better cover that point?

This has been fixed internally and will be available in the Fragment 1.3.0-alpha02 release.

In my project, I currently use onActivityCreated() to show/hide the app toolbar (with activity.supportActionBar.show()/activity.supportActionBarHide()). Is it safe to move that logic to onViewCreated() (as it is similar as onActivityCreated() from my understanding of previous comments), or should I add a lifecycle observer on the Activity?

Re #21 - certainly sounds like you want onViewCreated().

Re #23 - sounds like onViewCreated() is what you're looking for.