iOS Swift interop question: ``` Uncaught Kotlin exception: kotlin.native.IncorrectDereferenceExcepti...

# kotlin-native

[David Stolarsky]

iOS Swift interop question:

Uncaught Kotlin exception: kotlin.native.IncorrectDereferenceException: illegal attempt to access non-shared kotlin.collections.HashMap@8015aa08 from other thread

How do I go about avoiding this? Can I simply make the HashMap in question shared? Immutable? Freeze it? Throw a bunch of DispatchQueue.main.async { } wrappers everywhere?

The stack trace goes from Kotlin to Swift and back to Kotlin at least once, likely more than once.

The thread that is crashing is com.google.firebase.auth.globalWorkQueue

[Dominaezzz]

.freeze() it.

[kpgalligan]

freeze, or if you super need a shared map https://github.com/touchlab/Stately

[David Stolarsky]

silly question, can't find docs, what do my gradle and import line look like to make .freeze() available?

[kpgalligan]

freeze isn’t available in common code. Only native. Also in Stately: https://github.com/touchlab/Stately/blob/master/stately/src/commonMain/kotlin/co/touchlab/stately/Helpers.kt That lets you “freeze” from common code. Will do nothing on other platforms

[David Stolarsky]

interesting... can i just expect fun freeze(x: Any): Any and actual fun freeze(x: Any) = x.freeze()?

[David Stolarsky]

oh .freeze() does not exist on the android side i see

[kpgalligan]

The android side should just so nothing in it’s freeze actual

[kpgalligan]

https://github.com/touchlab/Stately/blob/master/stately/src/jvmMain/kotlin/co/touchlab/stately/HelpersJVM.kt#L19

[Paul Idstein]

If you receive a callback from an unknown iOS library, see https://github.com/JetBrains/kotlin-native/blob/d9263e0fc271540d55825d6de2d96215b4de5c0f/samples/objc/src/objcMain/kotlin/Window.kt#L80