I want to create a suspending function that calls `startActi

Question

I want to create a suspending function that calls `startActivityForResult` and it suspends until `onActivityResult` is called Is using a Channel the right way to do that ```kotlin class MyActivty Activity private val channel = Channel lt Uri gt override fun onActivityResult data Intent val uri = data data channel offer uri suspend fun soSthWithStartActivtyForResult Uri startActivityForResult intent 42 return channel receive ```

streetsofboston · Answer

I think I d use `suspendCancellableCoroutine` for this

Paul Woitaschek · Answer

And keep a list of continuations instead of the channel

streetsofboston · Answer

Yep But you can resume only once though Launching the activity and waiting for it again would require a new continuation

Paul Woitaschek · Answer

Btw there is `suspendCoroutine` there is nothing cancellable when calling `startActivityForResult`

streetsofboston · Answer

When your Activity goes away you may want to cancel it

streetsofboston · Answer

If not `suspendCoroutine` is good enough

streetsofboston · Answer

You d need some response for `soSthWithStartActivtyForResult` when the launching activity is cancelled i e onActivityResult is never called

streetsofboston · Answer

Something like this ``` class MyActivity Activity CoroutineScope by MainScope private var launchContinuation CancellableContinuation lt Uri gt = null override fun onActivityResult requestCode Int resultCode Int data Intent launchContinuation resume data data suspend fun soSthWithStartActivityForResult Uri = suspendCancellableCoroutine launchContinuation = it startActivityForResult intent 42 override fun onDestroy super onDestroy launchContinuation cancel ```

nulldev · Answer

louiscad · Answer

This will not survive lifecycle destroy unfortunately

hannesstruss · Answer

Yeah trying to coerce Android s request response APIs like runtime permissions or activity results into fluent callback APIs or Rx has been problematic for me in the past If your process dies and is restored your listener isn t registered anymore and your result is lost It s less elegant but safer to treat activity permission results as a hot channel that can emit anytime

louiscad · Answer

Runtime permissions are different because they are idempotent you can check if it s currently granted and requesting again will produce a success In fact I released a library for that yesteray night <https github com LouisCAD Splitties tree master modules permissions>

dekans · Answer

I did something related for runtime permission <https medium com geoffrey metais android runtime permissions in one suspending function b2774bb22e4b> With a headless retainInstance fragment you can survive rotation