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Kotlin Coroutines inside a Custom View with Lifecycle Awareness

👀 Views: 91 đŸ’Ŧ Answers: 1 📅 Created: 2025-06-17
kotlin coroutines android lifecycle Kotlin

I need some guidance on I'm performance testing and I've been struggling with this for a few days now and could really use some help. I'm having trouble using Kotlin Coroutines in a custom View that needs to be lifecycle aware. Specifically, I'm trying to launch a coroutine from the custom View's method, but it seems to be not respecting the lifecycle of the parent Fragment. When I try to collect a Flow from the coroutine, I get this behavior: `IllegalStateException: want to invoke collect while the CoroutineScope is cancelled`. Here's the relevant code from my custom view: ```kotlin class MyCustomView @JvmOverloads constructor( context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0 ) : View(context, attrs, defStyleAttr) { private var job: Job? = null fun startCollecting(flow: Flow<String>, lifecycleOwner: LifecycleOwner) { job = CoroutineScope(Dispatchers.Main).launch { flow.collect { value -> // Update UI with value println(value) } } lifecycleOwner.lifecycle.addObserver(object : LifecycleObserver { @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY) fun onDestroy() { job?.cancel() } }) } } ``` When I call `startCollecting(flow, this)` from my Fragment, it works fine initially, but if the Fragment goes to the background and comes back, it seems like the coroutine is still trying to collect, leading to the `IllegalStateException`. I tried using `viewLifecycleOwner` instead of `lifecycleOwner`, but it didn't resolve the scenario. Is there a recommended approach to make sure the coroutine stops collecting when the Fragment is no longer active? Am I missing something in managing the lifecycle? I'm using Kotlin 1.7.0 with AndroidX libraries. Any help would be appreciated! I'd really appreciate any guidance on this. Any ideas how to fix this? I'd really appreciate any guidance on this.