How to present an Alert in SwiftUI with no buttons

Question

I have a situation where I would like to recreate previous UIKit logic by displaying an Alert during a long running operation that the user cannot interact with.

Previously in UIKit, it would be this simple:

import UIKit

class ViewController: UIViewController {

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        let alertController = UIAlertController(title: "Loading",
                                                message: nil,
                                                preferredStyle: .alert)
        present(alertController, animated: true, completion: nil)
    }
}

And it looks like this:

A simple SwiftUI based version can be created as such:

import SwiftUI

struct ContentView: View {
    @State private var isLoading = true
    
    var body: some View {
        Text("Hello")
            .modifier(LoadingAlert(isPresented: $isLoading))
    }
}

struct LoadingAlert: ViewModifier {
    @Binding var isPresented: Bool

    func body(content: Content) -> some View {
        content
            .alert(isPresented: $isPresented) {
                Alert(title: Text(NSLocalizedString("Loading", comment: "")),
                      dismissButton: .none)
            }
    }
}

Whether I use nil or .none as the dismissButton argument, or completely omit the line, it will use a default OK button, and produce this:

I did modify the Alert arguments, sending in a button with an empty title, but this is the result, which is not as clean as I would like:

dismissButton: .default(Text("")))

Based on what I have seen, it does not appear that the Alert in SwiftUI supports what I want, based upon inspecting its initializers.

/// Creates an alert with one button.
public init(title: Text, message: Text? = nil, dismissButton: Alert.Button? = nil)

/// Creates an alert with two buttons.
///
/// - Note: the system determines the visual ordering of the buttons.
public init(title: Text, message: Text? = nil, primaryButton: Alert.Button, secondaryButton: Alert.Button)

For this project, the goal is to fully utilize SwiftUI, but it appears this is a scenario where we cannot get the desired result.

My take is either we will have to pull in a UIKit based AlertController, or use a different effect to indicate status. However, I'd love to be wrong here.

Answer 1

You can try this:

    var dialogMessage = UIAlertController(title: "Erro", message: "error description", preferredStyle: .alert)
        let window = UIApplication.shared.keyWindow
        window?.rootViewController?.present(dialogMessage, animated: true)
    }

Answer 2

I don't think an alert without a dismiss button in currently supported in SwiftUI, but you could create a custom view and present it with the same effect.

This library might help you out: https://github.com/exyte/PopupView