Hi,

I am absolutely lost trying to figure out how to pass the instance of NSManagedObjectContext from ContentView through to subviews specially ones being presented as a modal. From what I understand this is a bug/limitatin of SwiftUI/iOS13 at the moment.

ContentView calls the modal as follows:

.sheet(isPresented: $showLicenseManager) {
     () -> LicenseManagerView in
    let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    return LicenseManagerView().environment(\.managedObjectContext, context) as! LicenseManagerView
 }

and I am using accessing the NSManagedObjectContext instances as:

@Environment(\.managedObjectContext) var managedObjectContext

when I attempt to access the results of a FetchRequest defined as:

@FetchRequest(entity: License.entity(), sortDescriptors: [
    NSSortDescriptor(keyPath: \License.timestamp, ascending: false)
]) var licenses: FetchedResults<License>

in a list (note: the instance of Text is left there for testing purposes):

NavigationView {
    List {
        ForEach(licenses, id: \.name) { license in
            Text("Test")
        }
    }

I am met with the following error:

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x600001964be0 UIView:0x7fcd0a420380.width == - 16   (active)>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
Could not cast value of type 'SwiftUI.ModifiedContent<DemoApp.LicenseManagerView, SwiftUI._EnvironmentKeyWritingModifier<__C.NSManagedObjectContext>>' (0x7fcd0b09bf10) to 'NSManagedObjectContext' (0x7fff89c1c660).
2020-04-15 21:56:40.101515+1000 DemoApp[60019:3989730] Could not cast value of type 'SwiftUI.ModifiedContent<DemoApp.LicenseManagerView, SwiftUI._EnvironmentKeyWritingModifier<__C.NSManagedObjectContext>>' (0x7fcd0b09bf10) to 'NSManagedObjectContext' (0x7fff89c1c660)

Note: that I can perfectly well access the NSManagedObjectContext instance in the ContextView and have managed to build a list of entities from the above query and managed to add objects to the database.

Questions:

• What are ways in which we can pass the instance of NSManagedObjectContext from the ContentView to subviews, specially ones presented as modals
• Is the above approach in the right direction or have I missed the mark completely?

Any points will be much appreciaed. I seem to be going around in circles at the moment. Thank you for your time.

Thanks so much @Sangsom I didn't realise that

.sheet(isPresented: $showLicenseManager) { 
    LicenseManagerView().environment(\.managedObjectContext, self.managedObjectContext)
}

was a valid call. Much appreicate you taking time to respond.

FWIW, Apple considers this a bug, so it looks like modals might inherit environment from their parent in a future release.