huh, working on my swift code a bit, trying to get some navigation going, but the UI isn't reacting ...

# decompose

[Adam Brown]

huh, working on my swift code a bit, trying to get some navigation going, but the UI isn't reacting to the router state updating.

[Adam Brown]

@ObservedObject
    private var routerState: ObservableValue<ChildStack<AnyObject, ProjectRootDestination<AnyObject>>>

[Adam Brown]

private val stack = componentContext.childStack(
		source = navigation,
		initialConfiguration = Config.HomeConfig(projectDef),
		key = "ProjectRootRouter",
		childFactory = ::createChild
	)

	val state: Value<ChildStack<Config, ProjectRoot.Destination<*>>>
		get() = stack

	fun showNotes() {
		navigation.bringToFront(Config.NotesConfig(projectDef = projectDef))
	}

[Adam Brown]

I'm thinking it's because calling navigation.bringToFront isn't actually reassigning the variable maybe?

[Arkadii Ivanov]

Which variable? You can check the root component in samples.

[Adam Brown]

ya I was looking at counter example, but looking at the root one now, that seems much closer to what im doing here

[Adam Brown]

this variable, the router state: https://github.com/Wavesonics/hammer-editor/blob/bbooth-dev/ios/ios/ui/ProjectRoot/ProjectRootUi.swift#L17

[Adam Brown]

I even was just printing out which child was active in a textview, and it prints the initial one, but it never changes as I trigger navigations

[Adam Brown]

and this is the router: https://github.com/Wavesonics/hammer-editor/blob/bbooth-dev/common/src/commonMain/[…]rockstudios/apps/hammer/common/projectroot/ProjectRootRouter.kt

[Adam Brown]

hhmmm the main difference is that I'm using a StackView maybe

[Arkadii Ivanov]

Yeah, please try without StackView

[Adam Brown]

even still, stackview aside, that text view isn't even updating

[Adam Brown]

i just changed it to use that computed field:

[Adam Brown]

let curDest = destinationTitle(dest: activeDestination)
            Text(curDest)

[Adam Brown]

but no dice

[Arkadii Ivanov]

What if you remove Text("project root")?

[Arkadii Ivanov]

Also you can try adding logs everywhere, and see where it stops propagating

[Adam Brown]

im still working on this, logging on ios from kotlin wasnt working for me at first but i got that solved.

[Adam Brown]

i've got it logged down to where i make the navigate call, and thats all working

[Arkadii Ivanov]

Does Value emits the updated state on the Swift side?

[Adam Brown]

i dont think so, but i still need to verify that

[Adam Brown]

havent had a lot of time the last few days so havent been able to check much

[Arkadii Ivanov]

It would be useful if you could check that. Also worth checking any errors in Xcode logs.

[Adam Brown]

this should capture any update on the swift side I think:

[Adam Brown]

init(component: ProjectRoot, closeProject: @escaping () -> Void) {
        self.component = component
        self.routerState = ObservableValue(component.routerState)
        
        component.routerState.subscribe { stack in
            NSLog("swift router state update")
        }
    }

[Adam Brown]

as long as thats not wrong in some way, then the update is never getting back to the swift side of things

[Adam Brown]

I see the initial state update in that subscribe, but nothing after

[Arkadii Ivanov]

Is the back reproducible on github?

[Adam Brown]

ya, this branch is where the ios work is: https://github.com/Wavesonics/hammer-editor/tree/bbooth-dev

[Adam Brown]

im guessing there is no good way to debug into kotlin code from an ios build?

[Adam Brown]

wonder if its a threading issue or something...

[Arkadii Ivanov]

I remember there was KMP plugin for IDEA, but I never used it.

[Arkadii Ivanov]

Let me check the project

[Adam Brown]

ProjectRootUi.swift is the main swift file here

[Adam Brown]

ProjectRootComponent.kt is where the router lives

[Adam Brown]

maybe I'm not initializing something, like the lifecycle stuff

[Adam Brown]

huh i think it might be lifecycle related, im getting onDestroy called right after init

[Arkadii Ivanov]

Yep, when the parent is destroyed, all routers unsubscribe from navigation sources (e.g. StackNavigation)

[Adam Brown]

ah and that makes sense

[Arkadii Ivanov]

You can add lifecycle.doOnDestroy { Exception().printStackTrace() } to identify the cause.

[Arkadii Ivanov]

Let me know if you still need any help.

[Adam Brown]

awesome, thanks for pointing me in the right direction!

[Adam Brown]

so I think the issue is that I was creating the component holder in the UI body function, so when it updates, it creates a new component, thus destroying the old one

[Adam Brown]

my use case here is a bit strange, I have two top level Components. on Desktop there are two separate windows, on android two separate Activities. on iOS they are currently just switched between based on state in the SwiftUi code it's self. So I need to find a way to create or destroy these components based on the state updates. Pretty new to both swift and swift UI, so probably just writing some hilarious naive code here

[Adam Brown]

ya moved the component creation out, looks like its working now

[Arkadii Ivanov]

Makes sense! You can try wrapping both roots into a separate struct that extends ObservableObject. Then put that wrapper into a separate View with StateObject annotated property. You can also expose component states from wrappers using State property.

[Arkadii Ivanov]

Check out similar example, not Decompose but similar use case - https://github.com/badoo/Reaktive/blob/8fdd1bc9613466f25813b8e3ad8722501d0ac85e/sample-ios-app/sample-ios-app/ContentView.swift#L59

[Adam Brown]

ya that sounds like pretty much what i did, they just live in this state obj now: https://github.com/Wavesonics/hammer-editor/blob/bbooth-dev/ios/ios/Root.swift#L12

[Arkadii Ivanov]

It looks like you can avoid MutableValue in your RootHolder. You can have @Published property.

[Adam Brown]

oh ya good call

[Adam Brown]

i have no idea what im doing in swift 😂