OnAppear and OnDisappear are not triggered on first view transition

Question

I have a watchOS App which uses the following layout:

NavigationView {
    if !HKHealthStore.isHealthDataAvailable() {
        ContentNeedHealthKitView()
    } else if !isAuthorized {
        ContentUnauthorizedView()
    } else {
        TabView(selection: $selection) {
            WeightView()
                .navigationTitle("Weight")
                .tag(1)
                .onAppear {
                    print("Appear!")
                }
                .onDisappear {
                    print("Disappear!")
                }
            SettingsView()
                .navigationTitle("Settings")
                .tag(2)
        }
    }
}

Unfortunately, the OnAppear and OnDisappear actions are only executed after transitioning from on view to another the second time. When swiping right the first time, nothing happens.

You should put this at the end of the navigation view – Raja Kishan May 17 '21 at 12:25 — Raja Kishan, May 17 '21 at 12:25

score 0 · Answer 1 · answered May 17 '21 at 12:26

You should provide a minimal reproducible example (see https://stackoverflow.com/help/minimal-reproducible-example).

Also your lines are producing compiler errors. The correct way to use onAppear is like this:

.onAppear {

}

Here is a working example, everything is working as expected. You should also place the onAppear ViewModifier to the child view.

import SwiftUI

struct WeightView: View {
    var body: some View {
        Text("WeightView")
         .onAppear {
            print("Appear!")
         }
         .onDisappear {
            print("Disappear!")
         }
    }
}

struct SettingsView: View {
    var body: some View {
        Text("SettingsView")
    }
}

struct ContentView: View {
    @State var selection = 1
    @State var isAuthorized = false

    var body: some View {
        NavigationView {
            if !isAuthorized {
                Button("authorize") {
                    isAuthorized.toggle()
                }
            } else {
                TabView(selection: $selection) {
                    WeightView()
                        .navigationTitle("Weight")
                        .tag(1)
                    SettingsView()
                        .navigationTitle("Settings")
                        .tag(2)
                }
            }
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

OnAppear and OnDisappear are not triggered on first view transition

1 Answers1