EnvironmentObject Causes SwiftUI App to Crash When Launched in the Background

I'm seeing the same issue but my app is launched in the background using the WatchConnectivity framework. I think this is a clear bug. Did you file a radar?

I'm finding this exact situation, in an app being background-launched in response to CloudKit attempting to update my SwiftData-based storage after the watchOS variant synchronizes a new record upstream, and the iOS app attempts to persist that record.

I will look at the environment object usage in my ContentView.

To my knowledge, there is no way to avoid instantiating a ContentView in a SwiftUI app, right? For instance, handling background functionality without any UI.

Another developer is finding something similar. https://stackoverflow.com/questions/78265564/background-crash-swiftdata-swiftui-one-time-initialization-function-for-empty

I am seeing this exact same problem with my SwiftData app. I am using a .modelContext from the root container, instead of an .environmentObject or .environment() but all other symptoms are the same.

Same here. Starting with iOS 17.4, my app waking in the background would crash when accessing an invalid modelContext environment variable. Even moving the app into the background with recent SwiftData changes (especially changes to Relationships) caused the same crash. My guess is that an autoSave is triggered? Easier to reproduce on iPad.

My workaround, based on the helpful discussion above....

• Create a globally accessible modelContext and modelContainer. In my case I created a singleton "DataCenter" object created in the first line of the app's init.
• Remove ALL @Environment(.modelContext) private var modelContext from your project
• Add the modelContainer modifier to the WindowGroup, in my case WindowGroup{...}.modelContainer(DataCenter.shared.container)
• Use that global context directly when needed, such as DataCenter.shared.context.insert(...)

Half measures didn't work for me, such as just removing the modelContext environment variable from the root view. Had to **** it entirely in the project.

Thanks for submitting the bug report @squirepinto, Another alternative workaround would be to specify a defaultValue and use the EnvironmentKey. This way there's an instantiated default value available if text is accessed in the background and you can also set the environment value for a view and all its subviews.

@Observable
final class ArbitraryEnvValue {
    var text = "This is text"
}

private struct MyEnvironmentKey: EnvironmentKey {
    static let defaultValue: ArbitraryEnvValue = ArbitraryEnvValue()
}

@main
struct BackgroundEnvObjCrashApp: App {
    private let locationManager = LocationManager.shared
    @State private var envVal = ArbitraryEnvValue()
    
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .environment(\.myCustomValue, envVal)
    }
}


extension EnvironmentValues {
    var myCustomValue: ArbitraryEnvValue {
        get { self[MyEnvironmentKey.self] }
        set { self[MyEnvironmentKey.self] = newValue }
    }
}

struct ContentView: View {
    
    @Environment(\.myCustomValue) private var envVal: ArbitraryEnvValue
    var body: some View { 
     .....
     }
}

Hi, just a cross reference to my answer on this thread.

tl;dr: I could solve it by moving the view modifier from the WindowGroup to the ContentView. I have not tested it for the .environment view modifier.

Non crashing example:

import SwiftData
import SwiftUI

@main
struct ExampleApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
                .modelContainer(for: [Item.self])
        }
    }
}