Bind to property on first element in SwiftData @Query array

Question

I have a SwiftData model Player and there should only ever be 0 or 1 in the database. When the user is on the Main Menu and taps to Start a New Game, I walk them through a couple of screens to pick the options for the game. Once all of the options are chosen, I delete all existing Player objects and insert a new one. Then I dismiss all of those options picking screens.

Then what I want to happen is to automatically show the game view. But I'm not sure how to bind my .fullScreenCover() to the Player.isShown property on the first element in my SwiftData @Query.

The code below doesn't work because: Cannot convert value of type 'Bool?' to expected argument type 'Binding<Bool>'

I'm still very new to Swift and SwiftUI, so my grasp on bindables and observables is still tenuous.

struct RootContentView: View {
    @Query var activeplayers: [Player] // should only ever be 0 or 1

    var body: some View {
        ZStack {
            // stuff            
        }
        .fullScreenCover(isPresented: activeplayers.first?.isshown content: {
                GameView()
        })
        
    }
    
}

How can I automatically show my GameView screen based on the optional first element in my SwiftData @Query?

I also tried just querying to see if any players exist with .isShown == true and then binding to $activeplayers.isEmpty (this is the reverse of the logic I actually want, but I was just trying to find SOME way to distill the data down to a single bool property and I figured I could work on reversing the logic later) but that didn't work either:

@Query (filter: #Predicate<Player> {
        $0.isshown == true
    }) var activeplayers: [Player]

// ...

// without the $, gives the error: 
// Cannot convert value of type 'Bool' to expected argument type 'Binding<Bool>'
.fullScreenCover(isPresented: activeplayers.isEmpty content: {
        GameView()
})

// with the $, gives the error:
// Cannot find '$activeplayers' in scope
.fullScreenCover(isPresented: $activeplayers.isEmpty content: {
        GameView()
})

workingdog support Ukraine · Accepted Answer · 2023-11-28 07:41:46Z

3

You could try this simple approach, using an extra @State var shouldShow and setting it in .onAppear {...} as shown in the example code

struct RootContentView: View {
    @Environment(\.modelContext) private var modelContext
    @Query var activeplayers: [Player]
    
    @State var shouldShow = false // <-- here
    
    var body: some View {
        VStack {
            Text("testing")
        }
        .fullScreenCover(isPresented: $shouldShow) {  // <-- here
            GameView()
        }
        // -- here
        .onAppear {
            if let player = activeplayers.first, let doShow = player.isshown {
                shouldShow = doShow
            }
        }
    }
}

answered Nov 28, 2023 at 7:41

workingdog support Ukraine

38.9k5 gold badges47 silver badges52 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Kenny Wyland Over a year ago

Ah! Neat. So much to learn about SwiftUI. This seems like a good solution in general. In my specific case, it didn't work out because onAppear doesn't get called when the subsequent screens are dismissed (because of the pageSheet presentation). But the sheet() action allows me to add a dismiss handler and then I can put your suggested solution into that. My code above shows fullScreenCover() instead of sheet(), so I accepted your solution. The original code design was using sheet() but I had experimented with fullScreenCover() to see if I could get things working and forgot to change above.

Collectives™ on Stack Overflow

Bind to property on first element in SwiftData @Query array

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related