Refactor navigation to allow implementation in iOS side

Author: hichamboushaba

androidApp/src/main/java/com/hicham/wcstoreapp/android/di/AppModule.kt

@@ -8,9 +8,7 @@ import com.hicham.wcstoreapp.data.currencyformat.CurrencyFormatProvider
 import com.hicham.wcstoreapp.data.currencyformat.StoreCurrencyFormatProvider
 import com.hicham.wcstoreapp.di.AppCoroutineScopeQualifier
 import com.hicham.wcstoreapp.ui.NavigationManager
-import kotlinx.coroutines.GlobalScope
 import org.koin.dsl.module
-import org.koin.dsl.single
 
 val appModule = module {
     single<NavigationManager> { get<AndroidNavigationManager>() }

androidApp/src/main/java/com/hicham/wcstoreapp/android/ui/navigation/AndroidNavigationManager.kt

@@ -6,7 +6,14 @@ import androidx.navigation.NavOptions
 import androidx.navigation.NavOptionsBuilder
 import androidx.navigation.navOptions
 import com.hicham.wcstoreapp.ui.NavigationManager
+import io.ktor.utils.io.core.*
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.launch
+import kotlin.coroutines.EmptyCoroutineContext
 
 class AndroidNavigationManager : NavigationManager {
     // We use a StateFlow here to allow ViewModels to start observing navigation results before the initial composition,
@@ -16,6 +23,7 @@ class AndroidNavigationManager : NavigationManager {
     private val navigationCommands =
         MutableSharedFlow<NavigationCommand>(extraBufferCapacity = Int.MAX_VALUE)
 
+    private val navigationResults = Channel<NavigationResult>(capacity = Channel.BUFFERED)
 
     suspend fun handleNavigationCommands(navController: NavController) {
         navigationCommands
@@ -43,7 +51,7 @@ class AndroidNavigationManager : NavigationManager {
         navigationCommands.tryEmit(NavigationCommand.PopUpToRoute(route, inclusive))
     }
 
-    override fun <T> navigateBackWithResult(
+    override fun <T: Any> navigateBackWithResult(
         key: String,
         result: T,
         destination: String?
@@ -57,23 +65,20 @@ class AndroidNavigationManager : NavigationManager {
         )
     }
 
-    override fun <T> observeResult(key: String, route: String?): Flow<T> {
-        return navControllerFlow
-            .filterNotNull()
-            .flatMapLatest { navController ->
-                val backStackEntry = route?.let { navController.getBackStackEntry(it) }
-                    ?: navController.currentBackStackEntry
-
-                backStackEntry?.savedStateHandle?.let { savedStateHandle ->
-                    savedStateHandle.getLiveData<T?>(key)
-                        .asFlow()
-                        .filter { it != null }
-                        .onEach {
-                            // Nullify the result to avoid resubmitting it
-                            savedStateHandle.set(key, null)
-                        }
-                } ?: emptyFlow()
+    override fun <T: Any> observeResult(
+        key: String,
+        route: String?,
+        onEach: (T) -> Unit
+    ): Closeable {
+        val scope = CoroutineScope(Dispatchers.Main)
+        navigationResults.receiveAsFlow()
+            .filter { it.key == key }
+            .onEach {
+                (it.value as? T)?.let(onEach)
             }
+            .launchIn(scope)
+
+        return Closeable { scope.cancel() }
     }
 
     private fun NavController.handleNavigationCommand(navigationCommand: NavigationCommand) {
@@ -88,12 +93,11 @@ class AndroidNavigationManager : NavigationManager {
                 navigationCommand.inclusive
             )
             is NavigationCommand.NavigateUpWithResult<*> -> {
-                val backStackEntry =
-                    navigationCommand.destination?.let { getBackStackEntry(it) }
-                        ?: previousBackStackEntry
-                backStackEntry?.savedStateHandle?.set(
-                    navigationCommand.key,
-                    navigationCommand.result
+                navigationResults.trySend(
+                    NavigationResult(
+                        navigationCommand.key,
+                        navigationCommand.result
+                    )
                 )
 
                 navigationCommand.destination?.let {
@@ -104,14 +108,16 @@ class AndroidNavigationManager : NavigationManager {
             }
         }
     }
+
+    private data class NavigationResult(val key: String, val value: Any)
 }
 
 sealed class NavigationCommand {
     object NavigateUp : NavigationCommand()
     data class NavigateToRoute(val route: String, val options: NavOptions? = null) :
         NavigationCommand()
 
-    data class NavigateUpWithResult<T>(
+    data class NavigateUpWithResult<T: Any>(
         val key: String,
         val result: T,
         val destination: String? = null

iosApp/WCStoreApp.xcodeproj/project.pbxproj

@@ -304,6 +304,7 @@
 				MTL_ENABLE_DEBUG_INFO = INCLUDE_SOURCE;
 				MTL_FAST_MATH = YES;
 				ONLY_ACTIVE_ARCH = YES;
+				OTHER_LDFLAGS = "-lsqlite3";
 				SDKROOT = iphoneos;
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = DEBUG;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
@@ -358,6 +359,7 @@
 				IPHONEOS_DEPLOYMENT_TARGET = 15.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				MTL_FAST_MATH = YES;
+				OTHER_LDFLAGS = "-lsqlite3";
 				SDKROOT = iphoneos;
 				SWIFT_COMPILATION_MODE = wholemodule;
 				SWIFT_OPTIMIZATION_LEVEL = "-O";

iosApp/WCStoreApp/IOSNavigationManager.swift

@@ -37,6 +37,18 @@ class IOSNavigationManager: NavigationManager, ObservableObject {
         navigationStack.pop(to: PopDestination.view(withId: route))
     }
 
+    func navigateBackWithResult(key: String, result: Any, destination: String?) {
+        // TODO
+    }
+    
+    func observeResult(key: String, route: String?, onEach: @escaping (Any) -> Void) -> Ktor_ioCloseable {
+        // TODO
+        return closeable {
+            
+        }
+    }
+
+            
     @ViewBuilder
     func getView(iOSScreen: IOSScreen, arguments: Dictionary<String, String>) -> some View {
         switch iOSScreen {
@@ -90,3 +102,13 @@ enum IOSScreen: String, CaseIterable {
         }
     }
 }
+
+class closeable : Ktor_ioCloseable {
+    private var closeCallback:() -> Void
+    init(closeCallback: @escaping () -> Void) {
+        self.closeCallback = closeCallback
+    }
+    func close() {
+        self.closeCallback()
+    }
+}

shared/src/commonMain/kotlin/com/hicham/wcstoreapp/ui/NavigationManager.kt

@@ -1,15 +1,29 @@
 package com.hicham.wcstoreapp.ui
 
+import io.ktor.utils.io.core.*
+import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.callbackFlow
 
 interface NavigationManager {
     fun navigate(route: String)
     fun navigateUp()
     fun popUpTo(route: String, inclusive: Boolean = false)
-    fun <T> navigateBackWithResult(
+    fun <T : Any> navigateBackWithResult(
         key: String,
         result: T,
         destination: String? = null
     )
-    fun <T> observeResult(key: String, route: String? = null): Flow<T>
+
+    fun <T : Any> observeResult(key: String, route: String? = null, onEach: (T) -> Unit): Closeable
+}
+
+fun <T : Any> NavigationManager.observeResultAsFlow(key: String, route: String? = null): Flow<T> {
+    return callbackFlow {
+        val closeable = observeResult<T>(key, route) {
+            trySend(it)
+        }
+
+        awaitClose { closeable.close() }
+    }
 }

shared/src/commonMain/kotlin/com/hicham/wcstoreapp/ui/checkout/CheckoutViewModel.kt

@@ -6,10 +6,7 @@ import com.hicham.wcstoreapp.data.checkout.CheckoutRepository
 import com.hicham.wcstoreapp.data.currencyformat.CurrencyFormatProvider
 import com.hicham.wcstoreapp.models.Address
 import com.hicham.wcstoreapp.models.PaymentMethod
-import com.hicham.wcstoreapp.ui.BaseViewModel
-import com.hicham.wcstoreapp.ui.CurrencyFormatter
-import com.hicham.wcstoreapp.ui.NavigationManager
-import com.hicham.wcstoreapp.ui.ShowSnackbar
+import com.hicham.wcstoreapp.ui.*
 import com.hicham.wcstoreapp.ui.checkout.address.AddAddressViewModel
 import com.hicham.wcstoreapp.ui.navigation.Screen
 import kotlinx.coroutines.flow.*
@@ -59,7 +56,7 @@ class CheckoutViewModel constructor(
 
     private fun observeShippingAddress() {
         // Observe Added Address
-        navigationManager.observeResult<Address>(AddAddressViewModel.ADDRESS_RESULT)
+        navigationManager.observeResultAsFlow<Address>(AddAddressViewModel.ADDRESS_RESULT)
             .onEach {
                 addressRepository.setPrimaryShippingAddress(it)
             }.launchIn(viewModelScope)

shared/src/commonMain/kotlin/com/hicham/wcstoreapp/ui/checkout/address/AddressListViewModel.kt

@@ -6,6 +6,7 @@ import com.hicham.wcstoreapp.ui.BaseViewModel
 import com.hicham.wcstoreapp.ui.NavigationManager
 import com.hicham.wcstoreapp.ui.ShowSnackbar
 import com.hicham.wcstoreapp.ui.navigation.Screen
+import com.hicham.wcstoreapp.ui.observeResultAsFlow
 import kotlinx.coroutines.flow.*
 import kotlinx.coroutines.launch
 
@@ -35,7 +36,7 @@ class AddressListViewModel(
 
     private fun observeSelectedAddress() {
         // Observe navigation result
-        navigationManager.observeResult<Address>(AddAddressViewModel.ADDRESS_RESULT)
+        navigationManager.observeResultAsFlow<Address>(AddAddressViewModel.ADDRESS_RESULT)
             .onStart {
                 val defaultAddress = //savedStateHandle.get<Address>("address")
                      addressRepository.primaryShippingAddress.first()