Custom Back button Action in SwiftUI

There is no easy way to perform a custom action when the navigation view Back button is pressed.

I think that's because Apple wants the behavior of a navigation view for every app in the ecosystem to be the same.

That means if you want a custom action for the back button, you have to opt out of the default back button.

And that's what we are going to do in this article.

Custom Back button Action in SwiftUI

To have a custom back button action, you need to do two things.

1. Opt-out of a default back button.
2. Recreate a back button yourself with new action.

Remove the default Back button

To remove the default back button, you apply .navigationBarBackButtonHidden(true) to the view that you want to hide the back button.

In the following example, we set .navigationBarBackButtonHidden(true) to a DetailView. So, when it gets pushed to a navigation stack, it won't have the back button.

struct DetailView: View {
    var body: some View {
        Text("Detail View")
            .navigationBarBackButtonHidden(true)
            .navigationTitle("Detail Title")
    }
}

Recreate a Back button

A back button is just a button. To recreate it, we just need to create a normal button and position it on the leading edge of a navigation bar.

We can do that with a help of toolbar(content:) and ToolbarItem(placement: .navigationBarLeading).

struct DetailView: View {
    var body: some View {
        Text("Detail View")
            .navigationBarBackButtonHidden(true)
            .navigationTitle("Detail Title")
            // 1
            .toolbar {
                // 2
                ToolbarItem(placement: .navigationBarLeading) {
                    Button {
                        // 3
                        print("Custom Action")
                    } label: {
                        // 4
                        HStack {
                            Image(systemName: "chevron.backward")
                            Text("Custom Back")
                        }
                    }
                }
            }
    }
}

1 We use toolbar(content:) to add a new toolbar item.
2 We position this to .navigationBarLeading, which is the same position as the default back button.
3 This is where we implement a custom action.
4 We try replicating the default back button with an arrow image and text.

Here is the example of the code above. As you can see, the default back button is replaced with our own implementation.

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Caveat

Once you hide the default back button, all the back button functions are gone.

• Tapping on your custom back button won't pop the view out of a navigation stack.
• Swiping from the leading edge to go back is also disabled.

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How to dismiss the view

If you want to dismiss the view, you can use either DismissAction or PresentationMode based on the minimum iOS version you supported.

iOS 15: DismissAction

struct DetailView: View {
    // 1
    @Environment(\.dismiss) private var dismiss
    
    var body: some View {
        Text("Detail View")
            .navigationBarBackButtonHidden(true)
            .navigationTitle("Detail Title")
            .toolbar {
                ToolbarItem(placement: .navigationBarLeading) {
                    Button {
                        print("Custom Action")
                        // 2
                        dismiss()
                    } label: {
                        HStack {
                            Image(systemName: "chevron.backward")
                            Text("Custom Back")
                        }
                    }
                }
            }
    }
}

1 Declare the dismiss environment value.
2 Then call dismiss() to perform the dismissal.

iOS 13-14: PresentationMode

DismissAction was introduced in iOS 15. For the older versions, we need to use PresentationMode.

struct DetailView: View {
    // 1
    @Environment(\.presentationMode) var presentationMode
    
    var body: some View {
        Text("Detail View")
            .navigationBarBackButtonHidden(true)
            .navigationTitle("Detail Title")
            .toolbar {
                ToolbarItem(placement: .navigationBarLeading) {
                    Button {
                        print("Custom Action")
                        // 2
                        presentationMode.wrappedValue.dismiss()
                    } label: {
                        HStack {
                            Image(systemName: "chevron.backward")
                            Text("Custom Back")
                        }
                    }
                }
            }
    }
}

1 Declare the presentationMode environment value.
2 Then call presentationMode.wrappedValue.dismiss() to perform the dismissal.