CODEWITHSUNDEEP
iosmultithreadinggrand-central-dispatchkotlin-coroutineskotlin-multiplatform
Marcus
Marcus

Reputation: 33

How to run a task in background thread on iOS app using Kotlin-Multiplatform?

I've been trying to run tasks in a Kotlin-Multiplatform lib on a background thread on the iOS project and ran into some problems:

I tried using both Kotlin-Coroutines and the platform libs for GCD and have only been able to run tasks in the the main thread in iOS. Whenever I try sending something asynchronously to a background thread, the iOS app crashes with the following error:

"kotlin.native.IncorrectDereferenceException: illegal attempt to access non-shared com.hp.jarvis.kmm.LogFile.$saveLog$lambda-0$FUNCTION_REFERENCE$9@155a948 from other thread"

Upvotes: 3

Views: 2076

Answers (1)

Róbert Nagy
Róbert Nagy

Reputation: 7700

IncorrectDereferenceException is basically a signal that you're trying to access a global state from a background thread.

You could play around with:

  • @ThreadLocal -> Makes a copy for every thread of a specific object
  • @SharedImmutable -> Will froze your object and make it available for all threads, note that if you'll try to change the value of a frozen object you'll get InvalidMutabilityException

I'd definitely give a read for this blog to understand the current memory model: https://touchlab.co/kotlin-native-concurrency/

Upvotes: 4

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