How do I present a UIAlertController in SwiftUI? - swift

Question

In UIKit, it is common to present UIAlertController for modal pop up alert messages in response to some action.
Is there a modal alert controller type in SwiftUI?
Is there a way to present a UIAlertController from SwiftUI classes? It seems like this may be possible using UIViewControllerRepresentable but not sure if that is required?

Answer 1

This just works:
class func alertMessage(title: String, message: String) {
let alertVC = UIAlertController(title: title, message: message, preferredStyle: .alert)
let okAction = UIAlertAction(title: "OK", style: .default) { (action: UIAlertAction) in
}
alertVC.addAction(okAction)
let viewController = UIApplication.shared.windows.first!.rootViewController!
viewController.present(alertVC, animated: true, completion: nil)
}
Put it in a Helper-Class.
Usage:
Helper.alertMessage(title: "Test-Title", message: "It works - even in SwiftUI")

Answer 2

Use Alert instead.
import SwiftUI
struct SwiftUIView: View {
#State private var showAlert = false;
var body: some View {
Button(action: { self.showAlert = true }) {
Text("Show alert")
}.alert(
isPresented: $showAlert,
content: { Alert(title: Text("Hello world")) }
)
}
}
Bind to isPresented in order to control the presentation.

Answer 3

I'm using extension of UIViewController to get current vc and UIAlertController to present 'Alert'. Maybe you can try this as followings:
extension for UIViewController
extension UIViewController {
class func getCurrentVC() -> UIViewController? {
var result: UIViewController?
var window = UIApplication.shared.windows.first { $0.isKeyWindow }
if window?.windowLevel != UIWindow.Level.normal {
let windows = UIApplication.shared.windows
for tmpWin in windows {
if tmpWin.windowLevel == UIWindow.Level.normal {
window = tmpWin
break
}
}
}
let fromView = window?.subviews[0]
if let nextRespnder = fromView?.next {
if nextRespnder.isKind(of: UIViewController.self) {
result = nextRespnder as? UIViewController
result?.navigationController?.pushViewController(result!, animated: false)
} else {
result = window?.rootViewController
}
}
return result
}
}
extension for UIAlertController
extension UIAlertController {
//Setting our Alert ViewController, presenting it.
func presentAlert() {
ViewController.getCurrentVC()?.present(self, animated: true, completion: nil)
}
func dismissAlert() {
ViewController.getCurrentVC()?.dismiss(animated: true, completion: nil)
}
}
And you can create your showAlert function now
func showMyAlert() {
let myAlert = UIAlertController(title: "Confirm order", message: "Are you sure to order two box of chocolate?", preferredStyle: .alert)
let okAction = UIAlertAction(title: "Ok!", style: .default) { (_) in
print("You just confirm your order")
}
let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) { (_) in
print(You cancel it already!)
}
myAlert.addAction(okAction)
myAlert.addAction(cancelAction)
myAlert.presentAlert()
}
Wish my answer can help you. :-)

Answer 4

You can present UIKit Alert in SwiftUI using notificationCenter
At SceneDelegate.swift on "func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions)" insert this code {
NotificationCenter.default.addObserver(self, selector: #selector(self.showAlert), name: Notification.Name("showAlert"), object: nil)
and add this function
#objc private func showAlert(notification: NSNotification){
let msg: String = notification.object as! String
let alert = UIAlertController(title: "Title", message: msg, preferredStyle: .alert)
let cancelAction = UIAlertAction(title: "οκ", style: .cancel) { (action) in
}
alert.addAction(cancelAction)
DispatchQueue.main.async {
self.window?.rootViewController?.present(alert, animated: true, completion: nil)
}
}
Now you can make the app to appear a message with UIKit AlertController writing this code on an action in a swifui class
var body: some View {
Button(action:{
NotificationCenter.default.post(name: Notification.Name("showAlert"), object: "Ελέγξτε το δίκτυο σας και προσπαθήστε αργότερα.")
}
}