SwiftUI: Catalyst Alert Showing Duplicate Buttons and Not Triggering Action

Question

For some reason, the following code is displaying an Alert with three instances of the same button, none of which trigger the action (just a simple console output for an example) as expected:

Has anyone else experienced this? Any suggestions on a fix?

It's building on Xcode 11.2.1, for an iOS 13.0 target, then running on macOS (10.15.1) via Catalyst.

Update 1: This appears to be an issue specific to Catalyst. When the same code is run on an iPhone simulator, it shows one button and executes the action, as expected.

Update 2: The issue also wasn't fixed by updating to Xcode 11.3.1 and macOS 10.15.3.

public struct ContactUsView: View {
    
    @ObservedObject private var contactUsVM: ContactUsViewModel
    
    private var successAlert: Alert {
        Alert(
            title: Text("Email Sent"),
            message: Text("Thanks for taking the time to reach out to us. We appreciate it!"),
            dismissButton: .default(Text("OK")) {
                self.dismissSelf()
            }
        )
    }
    
    public var body: some View {
        Form {
            // ...
        }
        .alert(isPresented: self.$contactUsVM.contactAttemptSucceeded) {
            self.successAlert
        }
    }

    public init() {
        self.contactUsVM = ContactUsViewModel()
    }
    
    private func dismissSelf() {
        print("Dismissing!")
    }
}

class ContactUsViewModel: ObservableObject {

    @Published var contactAttemptSucceeded: Bool = true
}

Similar problem for me for Xcode 11.4.1 and MacOS 10.15.3, except my Alert has three sets of primary and secondary buttons. This is just on the Mac, looks fine on iOS. — WholeCheese, May 21 '20 at 20:04

score 1 · Answer 1 · answered May 28 '20 at 09:38

It seems that your code works fine on xCode 11.5 MacOs 0.15.4. If you run your example (I've just filled the hole in your code):

import SwiftUI

public struct ContactUsView: View {

    @ObservedObject private var contactUsVM: ContactUsViewModel

    private var successAlert: Alert {
        Alert(
            title: Text("Email Sent"),
            message: Text("Thanks for taking the time to reach out to us. We appreciate it!"),
            dismissButton: .default(Text("OK")) {
                self.dismissSelf()
            }
        )
    }

    public var body: some View {
        Form {
            Text("Hello World")
        }
        .alert(isPresented: self.$contactUsVM.contactAttemptSucceeded) {
            self.successAlert
        }
    }

    public init() {
        self.contactUsVM = ContactUsViewModel()
    }

    private func dismissSelf() {
        print("Dismissing!")
    }
}

class ContactUsViewModel: ObservableObject {

    @Published var contactAttemptSucceeded: Bool = true
}

You'll see this:

score 1 · Answer 2 · answered Dec 03 '20 at 15:48

This seems to be fixed on macOS Big Sur. Unfortunately, for those folks, who need to support macOS Catalina(me included), the only workaround is to create alert using UIAlertController.

The way I did that, is dispatching notification to SceneDelegate instance, and presenting UIAlertController on UIHostingController:

NotificationCenter.default.addObserver(forName: .showMailUnavailableAlert, object: nil, queue: nil) { [weak self] _ in
    let controller = UIAlertController(title: "Default email client is not configured.", preferredStyle: .alert)
    controller.addAction(.init(title: "Ok", style: .cancel, handler: nil))
    self?.window?.rootViewController?.present(controller, animated: true, completion: nil)
}

extension NSNotification.Name {
    static let showMailUnavailableAlert = NSNotification.Name("Email not configured.")
}

WholeCheese · Answer 3 · 2020-05-21T20:17:24.637

0

I don't know how to fix the duplicate buttons but to get the alert to dismiss you might need to add this line under the ObservedObject line:

@Environment(\.presentationMode) var presentationMode

and then add this:

presentationMode.wrappedValue.dismiss()

to your dismissSelf() func.

This is what I gleaned from a Hacking Swift video by Paul Hudson.

edited May 21 '20 at 20:17

answered May 21 '20 at 20:03

WholeCheese

437
3
14

Thanks, but that part I know. The point is that the method isn’t getting called even to do the log output. The functionality itself is only a secondary consideration to the broken alerts. – TheNeil Dec 03 '20 at 15:51

SwiftUI: Catalyst Alert Showing Duplicate Buttons and Not Triggering Action

3 Answers3