SwiftUI Changing State does not Dismiss Modal View

Question

I have a basic master/detail app with SwiftUI life cycle. On the detail page, I have a button to toggle an @State to present a modal for editing the detail item. I am using the fullScreenCover modal. The @State variable in the Detail view is passed as an @Binding to the Edit view.

The Edit view has a "Done" button to dismiss itself. I have tried coding with both the binding and presentationMode methods.

This all works except that on RARE occasions tapping the "Done" button does not dismiss the Edit view. I then have to hard close the app and restart. The edits which were made are still saved as expected. There is simply no way to move from that screen.

The Detail view calls the Edit view like this:

    .fullScreenCover(isPresented: $showEditModalView) {//showEditView
        InvItemEditView(showEditModalView: $showEditModalView,
                        invItem: self.invItem,
                        inputCategory1: self.inputCategory1).environment(\.managedObjectContext, managedObjectContext)
    }//full screen

The Done button is coded as this:

    Button(action: {
        
        self.saveEditedRecord()
        
            print("Before change - Done button showEditModalView is \(self.showEditModalView)")
        self.showEditModalView = false
            print("I got passed showEditModalView = false")
        self.presentationMode.wrappedValue.dismiss()
            print("I got passed presentationMode dismiss")
            print("After change - Done button showEditModalView is \(self.showEditModalView)")
    }) {
        Text("Done")
            .font(.system(size: 20))
    }//trailing button
    .disabled(self.localDisableSaveButton)
    .disabled(self.dataStore.pubDisableEditButton)

The saveEditedRecord does just that - it issues the Core Data saveContext.

I can't replicate the error on demand. It just happens occasionally. I was curious to see that the Button action always executes all lines of code - I had expected it to terminate once the variable controlling the view presentation changed. I searched for others who may have had issues with fullScreenCover but found nothing relavant. I added the print statements to see if there was an issue setting the @State variable. Here is an example console output:

CoreData: debug: CoreData+CloudKit: -[NSCloudKitMirroringDelegate managedObjectContextSaved:](2092): <NSCloudKitMirroringDelegate: 0x2837a8680>: Observed context save: <NSPersistentStoreCoordinator: 0x2827ab4f0> - <NSManagedObjectContext: 0x2837a9790>
in invItemEditView saveEditedRecord, in do after context.save
Before change - Done button showEditModalView is true
I got passed showEditModalView = false
I got passed presentationMode dismiss
After change - Done button showEditModalView is false

When it fails, the first console statement after the Core Data item is:

Before change - Done button showEditModalView is false

Any guidance would be appreciated. Xcode 12.4 iOS 14.4

Jonas Deichelmann Jonas Deichelmann · Accepted Answer · 2021-01-30T12:11:53

I guess the problem is that you missed adding the presentation environment in the SwiftUI Modal View.

Here is a complete example in SwiftUI:

struct ContentView: View {

  @State private var showEditModalView = false
  @Environment(\.presentationMode) var presentationMode

  var body: some View {
    Button(action: {
        self.showEditModalView = true
    }) {
        Text("Show modal")
    }.fullScreenCover(isPresented: $showEditModalView) {
        InvItemEditView()
    }
  }
}


struct InvItemEditView: View {

  @Environment(\.presentationMode) private var presentationMode

  var body: some View {
    Group {
      Text("Modal view")
      Button(action: {
         self.presentationMode.wrappedValue.dismiss()
      }) {
          Text("Done")
            .font(.system(size: 20))
      }
    }
  }
}

I would also suggest reading this question: SwiftUI dismiss modal

SwiftUI Changing State does not Dismiss Modal View

1 Answers