Delay function throws TypeCastException.

[horita-yuya]

The delay suspend function throws TypeCastException when called from Swift.

The Condition.

• preparing CoroutineDispatcher for main queue.
• launch coroutines using the dispatcher.

I prepared self-containing repository here.
https://github.com/horita-yuya/TempKotlinNativeReport
kotlinx.coroutines version: 1.1.0

[uncledoc]

The same problem but I think problem is in GlobalScope. There are my steps to reproduce:
1. Create multiplatform project for Android and iOS
2. Add dependencies org.jetbrains.kotlinx:kotlinx-coroutines-core-common:1.1.0, org.jetbrains.kotlinx:kotlinx-coroutines-android:1.1.0 and org.jetbrains.kotlinx:kotlinx-coroutines-core-native:1.1.0
3. Write a simple function in common or iOS module with body GlobalScope.launch { // some code or empty }
4. Try to call function in swift from iOS app

p.s. macos 10.14.2, xcode 10.1

[qwwdfsad]

It is a small regression introduced by #860.
An actual exception should be kotlin.IllegalStateException: There is no event loop. Use runBlocking { ... } to start one. because dispatcher does not implement Delay interface.

[horita-yuya]

I see. Thank you.

[ildarsharafutdinov]

Having that my mpp framework uses coroutines, what is the right way to "start event loop" on iOS?

What about the following? Is it a supposed way?

// somewhere in framework

fun appMain(mainBlock: () -> Unit) = runBlocking {
    mainBlock()
}

// main.m

int main(int argc, char * argv[]) {
    [MppKt appMainMainBlock:^MppKotlinUnit * {
    
        @autoreleasepool {
             result = UIApplicationMain(argc, argv, nil, @"MyAppDelegate");
        }
        return NULL;
    }];
}

[pardom]

An actual exception should be kotlin.IllegalStateException: There is no event loop. Use runBlocking { ... } to start one. because dispatcher does not implement Delay interface.

Given this restriction, how should I approach using this JVM/Native API while also supporting JS targets? Should I wrap my API with an expect/actual?

[pardom]

Not sure if this is my issue exactly, but I was linked here from JetBrains/kotlin-native#2752 in response to a bug manifested in oolong-kt/oolong#16. The project does not call delay as @qwwdfsad mentions above, but it also doesn't call runBlocking because I have no need to block and I also want to support all platforms.

[elizarov]

@pardom You don't need to block if you are using coroutines on the main (UI) thread in iOS, but you'll need to write the corresponding dispatcher. See here: #470 Does it help?