Fix SwiftUI environnementObject error crash on released app

Question

My app on AppStore got two crashes that look very similar.
This crash seems to append when I call function that use a environnement object SubscriptionManager.

By analysing the error stack I think It happens in the function safeAddExercice() when I try to get self.subscriptionManager that is the environnement object.

These are errors stacks :

Crash1

Crash2

That is the function safeAddExercice() :

Code Block private func safeAddExercice() {
				if Exercice.canAddNew(for: self.subscriptionManager) {
						self.showExerciceAdd = true
				}else{
						self.showMember = true
				}
		}

It's a function of ExerciceList :

Code Block struct ExerciceList: View {
		//some other environnement objects...
		@EnvironmentObject var subscriptionManager: SubscriptionManager
...
}

ExerciceList is an item of TabBar :

Code Block struct MainApp: View {
		//some other envObjects...
		@EnvironmentObject var subscriptionManager: SubscriptionManager
		...
		var body: some View {
				UIKitTabView{
						ExerciceList(selection: .constant(nil))
								.environment(\.managedObjectContext, managedObjectContext)
								.environmentObject(userSettings)
								.environmentObject(subscriptionManager)
								.tab(title: NSLocalizedString("My exercises", comment: ""), image: "dumbell")
...}
}

SubscriptionManager is instantiated in AppDelegate :

Code Block var subscriptionManager: SubscriptionManager = {
				SubscriptionManager()
		}()

And pass to MainApp in SceneDelegate:

Code Block let subscriptionManager = (UIApplication.shared.delegate as! AppDelegate).subscriptionManager
				
				let contentView = MainApp().environment(\.managedObjectContext, context)
						.environmentObject(subscriptionManager)
...

Crash appends both on iOS 13 and 14. I try to find a moment where I missed to inject object but I'm struggling a bit to find something.

1.9k

Posted by

langy

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Answer 1

Are you invoking safeAddExercice asynchronously? If so, the EnvironmentObjects may not be set at the time the callback is applied because it is not happening during the lifecycle of the view.

You could instead pass the environment object at the point when you schedule the exercise, thereby guaranteeing that the object will be available. E.g.:

Code Block var body: some View {
    Button("Add Exercise") {
        let subman = self.subscriptionManager
        DispachQueue.main.async {
            safeAddExercice(subman)
        }
    }
}
func safeAddExercice(_ subman: SubscriptionManager) {
    // operate on subman rather than self.subscriptionManager
}

Posted by

mprudhom

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Answer 2

I'm not doing asynchronously.
safeAddExercice() is call from .onTapGesture() and just passing true to state property linked to .sheet().

Posted by

langy

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Fix SwiftUI environnementObject error crash on released app

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