How to Implement Dismiss Callback for Sheet in iOS SwiftUI

In SwiftUI, sheets are a convenient way to present secondary views or modals. While it’s easy to show and dismiss sheets, you might want to execute some code when a sheet is dismissed.

This is where the onDismiss parameter comes in handy. In this blog post, we’ll explore how to implement a dismiss callback for sheets in SwiftUI using the onDismiss parameter.

Default Sheet Behavior

By default, SwiftUI provides a simple way to present sheets using the .sheet modifier. However, it doesn’t automatically notify you when the sheet is dismissed.

Add Dismiss Callback

Example Code

import SwiftUI

struct ContentView: View {
    @State private var showModal = false

    var body: some View {
        Button("Show Modal") {
            showModal.toggle()
        }
        .sheet(isPresented: $showModal, onDismiss: {
            print("Modal Closed!")
        }) {
            VStack{
                Text("Hello, I'm a modal!")
                Button("Dismiss") {
                    showModal = false
                }
            }
        }
    }
}

Code Explanation

• onDismiss: { print("Modal Closed!") }: The onDismiss parameter allows you to specify a closure that will be executed when the sheet is dismissed. In this example, it prints “Modal Closed!” to the console.
• Button("Dismiss") { showModal = false }: Inside the sheet, we have a button that sets the showModal state variable to false, effectively dismissing the sheet and triggering the onDismiss closure.

Why Use a Dismiss Callback?

Here are some reasons why you might want to use a dismiss callback:

• Data Refresh: You might need to refresh data or update the UI when a sheet is dismissed.
• Analytics: Tracking when a sheet is dismissed can provide valuable analytics data.
• User Experience: You might want to show a confirmation message or perform some other action when a sheet is dismissed to enhance the user experience.

The onDismiss parameter in SwiftUI provides a simple and effective way to execute code when a sheet is dismissed. Whether you need to refresh data, track analytics, or enhance the user experience, this parameter offers a straightforward solution.