Hi everyone Maybe someone can help me out with what are prob

Question

Hi everyone Maybe someone can help me out with what are probably Multiplatform beginner questions I just went through the <https play kotlinlang org hands on Networking 20and 20Data 20Storage 20with 20Kotlin 20Multiplatfrom 20Mobile 01 Introduction|Kotlin Multiplatform Hands on Networking and Data Storage> tutorial the Android build is running but iOS crashes at startup I ve been double and triple checking everything but I cannot find anything I did wrong Tbh I also have trouble understanding what the stacktrace tells me as in Which of the mentioned classes in there is the origin of the problem

Michael Pohl · Answer

```Function doesn t have or inherit Throws annotation and thus exception isn t propagated from Kotlin to Objective C Swift as NSError It is considered unexpected and unhandled instead Program will be terminated Uncaught Kotlin exception kotlin native concurrent InvalidMutabilityException mutation attempt of frozen kotlinx coroutines ChildHandleNode 12e2608 at 0 shared 0x0000000104b05f7d kfun kotlin Throwable lt init gt kotlin String + 93 Users teamcity buildAgent work cae0e6559deed4c4 runtime src main kotlin kotlin Throwable kt 23 37 at 1 shared 0x0000000104afeb2b kfun kotlin Exception lt init gt kotlin String + 91 Users teamcity buildAgent work cae0e6559deed4c4 runtime src main kotlin kotlin Exceptions kt 23 44 at 2 shared 0x0000000104afed7b kfun kotlin RuntimeException lt init gt kotlin String + 91 Users teamcity buildAgent work cae0e6559deed4c4 runtime src main kotlin kotlin Exceptions kt 34 44 at 3 shared 0x0000000104b3520b kfun kotlin native concurrent InvalidMutabilityException lt init gt kotlin String + 91 Users teamcity buildAgent work cae0e6559deed4c4 runtime src main kotlin kotlin native concurrent Freezing kt 22 60 at 4 shared 0x0000000104b356e2 ThrowInvalidMutabilityException + 690 Users teamcity buildAgent work cae0e6559deed4c4 runtime src main kotlin kotlin native concurrent Internal kt 92 11 at 5 shared 0x0000000104c2958c MutationCheck + 108 at 6 shared 0x0000000104d167b6 kfun kotlinx coroutines internal LinkedListNode lt set next gt kotlinx coroutines internal LinkedListNode + 102 opt buildAgent work 44ec6e850d5c63f0 kotlinx coroutines core native src internal LinkedList kt 19 28 at 7 shared 0x0000000104d16b3b kfun kotlinx coroutines internal LinkedListNode addLast kotlinx coroutines internal LinkedListNode + 283 opt buildAgent work 44ec6e850d5c63f0 kotlinx coroutines core native src internal LinkedList kt 31 9 at 8 shared 0x0000000104d16e86 kfun kotlinx coroutines internal LinkedListNode addOneIfEmpty kotlinx coroutines internal LinkedListNode kotlin Boolean + 230 opt buildAgent work 44ec6e850d5c63f0 kotlinx coroutines core native src internal LinkedList kt 47 9 at 9 shared 0x0000000104cc6ecf kfun kotlinx coroutines JobSupport promoteSingleToNodeList internal + 463 opt buildAgent work 44ec6e850d5c63f0 kotlinx coroutines core common src JobSupport kt 532 15 at 10 shared 0x0000000104cc5b2d kfun kotlinx coroutines JobSupport invokeOnCompletion kotlin Boolean kotlin Boolean kotlin Function1 lt kotlin Throwable kotlin Unit gt kotlinx coroutines DisposableHandle + 2061 opt buildAgent work 44ec6e850d5c63f0 kotlinx coroutines core common src JobSupport kt 470 25 at 11 shared 0x0000000104cc529f kfun kotlinx coroutines JobSupport invokeOnCompletion kotlin Function1 lt kotlin Throwable kotlin Unit gt kotlinx coroutines DisposableHandle + 207 opt buildAgent work 44ec6e850d5c63f0 kotlinx coroutines core common src JobSupport kt 449 9 at 12 shared 0x0000000104e62d14 kfun io ktor client HttpClient io ktor client engine HttpClientEngineFactory lt 0 0 gt kotlin Function1 lt io ktor client HttpClientConfig lt 0 0 gt kotlin Unit gt 0 lt io ktor client engine HttpClientEngineConfig gt io ktor client HttpClient + 1156 opt buildAgent work a85294440dc5c6e ktor client ktor client core common src io ktor client HttpClient kt 45 36 at 13 shared 0x0000000104ea5d0e kfun io ktor client HttpClient kotlin Function1 lt io ktor client HttpClientConfig lt gt kotlin Unit gt io ktor client HttpClient + 638 opt buildAgent work a85294440dc5c6e ktor client ktor client core posix src io ktor client HttpClient kt 18 46 at 14 shared 0x0000000104a7ad67 kfun com example multiplatformtest shared network SpaceXApi lt init gt + 199 at 15 shared 0x0000000104a6e6a7 kfun com example multiplatformtest shared SpaceXSDK lt init gt com example multiplatformtest shared cache DatabaseDriverFactory + 327 at 16 shared 0x0000000104a7f6a8 objc2kotlin 12 + 232 at 17 iosApp 0x000000010497e9f7 $sSo15SharedSpaceXSDKC21databaseDriverFactoryABSo0a8DatabaseeF0C tcfC + 39 at 18 iosApp 0x000000010497f4cb $s6iosApp13SceneDelegateCACycfc + 219 Users michaelpohl Development Misc MultiplatformTest iosApp iosApp SceneDelegate swift 5 0 at 19 iosApp 0x000000010497f573 $s6iosApp13SceneDelegateCACycfcTo + 19 at 20 UIKitCore 0x000000010ecde71d UIScene initWithSession connectionOptions + 709 at 21 UIKitCore 0x000000010fb0976b UIWindowScene initWithSession connectionOptions + 88 at 22 UIKitCore 0x000000010ece1f12 + UIScene sceneForFBSScene create withSession connectionOptions + 627 at 23 UIKitCore 0x000000010f88142b UIApplication connectUISceneFromFBSScene transitionContext + 1114 at 24 UIKitCore 0x000000010f88175a UIApplication workspace didCreateScene withTransitionContext completion + 289 at 25 UIKitCore 0x000000010f370c27 UIApplicationSceneClientAgent scene didInitializeWithEvent completion + 358 at 26 FrontBoardServices 0x0000000115d3a146 FBSScene callOutQueue agent didCreateWithTransitionContext completion + 391 at 27 FrontBoardServices 0x0000000115d62c0d 94 FBSWorkspaceScenesClient createWithSceneID groupID parameters transitionContext completion block invoke 176 + 102 at 28 FrontBoardServices 0x0000000115d47ba1 FBSWorkspace calloutQueue executeCalloutFromSource withBlock + 209 at 29 FrontBoardServices 0x0000000115d628db 94 FBSWorkspaceScenesClient createWithSceneID groupID parameters transitionContext completion block invoke + 352```

Michael Pohl · Answer

I understand that I need the Throws annotation for iOS to understand Exceptions but where am I missing any If I got right what I ve built going through the tutorial there is `SpaceXSDK` as the single point of entry to the shared module which one function is correctly anntoated I was unable to find a guide to debugging such problems properly is there a good resource on this Other things I noticed The `DatabaseDriverFactory` in the iOS package shows `com squareup sqldelight drivers` as an unresolved reference but it looks like that s an IDE error Same about the `AppDataBase kt` generated by SqolDelight It exists in the build folder and since at least the Android side compiles just fine I assume it works correctly Just wondering if that can also be generated into the actual source so that I don t have n IDE error any insights are much appreciated

Michael Pohl · Answer

oh if anyone is interested here s a <https github com michpohl kmm test|link> to my code it s just what I built following the tutorial

Samuel Michael · Answer

Throws Exception class suspend fun getLaunches forceReload Boolean List lt RocketLaunch gt val cachedLaunches = database getAllLaunches return if cachedLaunches isNotEmpty amp amp forceReload cachedLaunches else api getAllLaunches also database clearDatabase database createLaunches it

Samuel Michael · Answer

Slide in BuildingSDK page of tutorial

Samuel Michael · Answer

Nevermind that sounds like more of a concurrency thread issue see you have the correct annotation I mentioned above

Michael Pohl · Answer

yes I do I am actually wondering if this might be caused by any of the libraries given that this is all fast moving and very alpha But I haven t fully grasped Mutliplatform yet so I m a little lost atm

Sam · Answer

Are you using any threading or Grand Central Dispatch in your code A Kotlin object must be frozen before passing it between threads

Michael Pohl · Answer

I don t think so As stated above I just followed this very basic tutorial provided by jetbrains there is just a single api call and very basic ui

Michael Pohl · Answer

Ok I ve figured it out myself now Android Studio automatically added the import statements as I was typing but didn t always pick the correct one So I had to go through all the files and double check the imports since it all looked correct in the IDE