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@chriseidhof
Created April 20, 2020 12:33
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TextAlert
//
// ContentView.swift
//
// Created by Chris Eidhof on 20.04.20.
// Copyright © 2020 objc.io. All rights reserved.
//
import SwiftUI
import UIKit
extension UIAlertController {
convenience init(alert: TextAlert) {
self.init(title: alert.title, message: nil, preferredStyle: .alert)
addTextField { $0.placeholder = alert.placeholder }
addAction(UIAlertAction(title: alert.cancel, style: .cancel) { _ in
alert.action(nil)
})
let textField = self.textFields?.first
addAction(UIAlertAction(title: alert.accept, style: .default) { _ in
alert.action(textField?.text)
})
}
}
struct AlertWrapper<Content: View>: UIViewControllerRepresentable {
@Binding var isPresented: Bool
let alert: TextAlert
let content: Content
func makeUIViewController(context: UIViewControllerRepresentableContext<AlertWrapper>) -> UIHostingController<Content> {
UIHostingController(rootView: content)
}
final class Coordinator {
var alertController: UIAlertController?
init(_ controller: UIAlertController? = nil) {
self.alertController = controller
}
}
func makeCoordinator() -> Coordinator {
return Coordinator()
}
func updateUIViewController(_ uiViewController: UIHostingController<Content>, context: UIViewControllerRepresentableContext<AlertWrapper>) {
uiViewController.rootView = content
if isPresented && uiViewController.presentedViewController == nil {
var alert = self.alert
alert.action = {
self.isPresented = false
self.alert.action($0)
}
context.coordinator.alertController = UIAlertController(alert: alert)
uiViewController.present(context.coordinator.alertController!, animated: true)
}
if !isPresented && uiViewController.presentedViewController == context.coordinator.alertController {
uiViewController.dismiss(animated: true)
}
}
}
public struct TextAlert {
public var title: String
public var placeholder: String = ""
public var accept: String = "OK"
public var cancel: String = "Cancel"
public var action: (String?) -> ()
}
extension View {
public func alert(isPresented: Binding<Bool>, _ alert: TextAlert) -> some View {
AlertWrapper(isPresented: isPresented, alert: alert, content: self)
}
}
struct ContentView: View {
@State var showsAlert = false
var body: some View {
VStack {
Text("Hello, World!")
Button("alert") {
self.showsAlert = true
}
}
.alert(isPresented: $showsAlert, TextAlert(title: "Title", action: {
print("Callback \($0 ?? "<cancel>")")
}))
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
@quintuschen
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If I put .alert on a view, say, a VStack that does not take the whole screen, it will add a padding on top and bottom of the VStack. Is there any way to get around with that?

@skywalkerlw
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There's a problem: the navigation bar title will never come in this case.

@chriseidhof
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Author

Hm, I'm not sure, I haven't looked at this code in a long time...

@LucasCoelho
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this somehow makes my hidden navigation bar appear even without presenting the alert

@daviscdev
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daviscdev commented Sep 16, 2021

Set the UIHostingController background color to clear will fix some black cover issue

func makeUIViewController(context: UIViewControllerRepresentableContext<AlertWrapper>) -> UIHostingController<Content> {
        let hosting = UIHostingController(rootView: content)
        hosting.view.backgroundColor = .clear
        return hosting
    }

@skirsche-ieffects
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skirsche-ieffects commented May 23, 2022

When I try it on iOS 15, it does not work well with the automatic keyboard avoidance introduced in iOS 14. The SwiftUI views below the alert move around when the keyboard for the alert's text field appears.

Other than wrapping everything in a ScrollView, the only workaround I've seen so far is setting .ignoresSafeArea(.keyboard) in combination with this:
https://steipete.com/posts/disabling-keyboard-avoidance-in-swiftui-uihostingcontroller/

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