Add alert-like SwiftUI modfier to present a notification + example, fixes #143

Author: calimarkus

ExampleProject/ExamplesScreen.swift

@@ -25,6 +25,7 @@ struct ExamplesScreen: View {
   @State var showActivity = false
   @State var showSubtitle = false
   @State var backgroundType: StatusBarNotificationBackgroundType = .pill
+  @State var showStateDrivenNotification = false
 
   func showDefaultNotification(_ text: String, completion: @escaping (NotificationPresenter) -> ()) {
     let styleName = NotificationPresenter.shared.addStyle(named: "default_sample") { style in
@@ -243,6 +244,32 @@ struct ExamplesScreen: View {
             NotificationPresenter.shared.dismiss(after: 2.5)
           }
         }
+
+        Button {
+          showStateDrivenNotification.toggle()
+        } label: {
+          Toggle(isOn: $showStateDrivenNotification) {
+            Text("State driven presentation")
+              .font(.subheadline)
+
+            Text("A .notification() view modifier")
+              .font(.caption2)
+              .foregroundColor(.secondary)
+          }
+        }
+        .buttonStyle(PlainButtonStyle())
+        .notification(isPresented: $showStateDrivenNotification, style: {
+          $0.backgroundStyle.backgroundColor = .systemTeal
+          $0.backgroundStyle.pillStyle.minimumWidth = 100.0
+        }) {
+          Text("✨ So simple!")
+            .font(.subheadline)
+            .bold()
+            .foregroundStyle(.white)
+            .lineLimit(0)
+            .minimumScaleFactor(0.66)
+            .padding([.leading, .trailing], 20)
+        }
       }
 
       Section("Custom Style Examples") {

JDStatusBarNotification.xcodeproj/project.pbxproj

@@ -7,6 +7,8 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		2884CAC02D04DCA5005E00A6 /* NotificationViewExtension.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2884CABF2D04DCA5005E00A6 /* NotificationViewExtension.swift */; };
+		2884CAC12D04DCA5005E00A6 /* NotificationViewExtension.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2884CABF2D04DCA5005E00A6 /* NotificationViewExtension.swift */; };
 		28D81A942B010C7500DE2CDF /* DiscoveryHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 28D81A932B010C7500DE2CDF /* DiscoveryHelper.swift */; };
 		28D81A952B0110C700DE2CDF /* DiscoveryHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 28D81A932B010C7500DE2CDF /* DiscoveryHelper.swift */; };
 		28D81A9B2B01217100DE2CDF /* NotificationWindow.swift in Sources */ = {isa = PBXBuildFile; fileRef = 28D81A9A2B01217100DE2CDF /* NotificationWindow.swift */; };
@@ -200,6 +202,7 @@
 /* End PBXCopyFilesBuildPhase section */
 
 /* Begin PBXFileReference section */
+		2884CABF2D04DCA5005E00A6 /* NotificationViewExtension.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NotificationViewExtension.swift; sourceTree = "<group>"; };
 		28D81A932B010C7500DE2CDF /* DiscoveryHelper.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DiscoveryHelper.swift; sourceTree = "<group>"; };
 		28D81A9A2B01217100DE2CDF /* NotificationWindow.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NotificationWindow.swift; sourceTree = "<group>"; };
 		28D81A9D2B01257A00DE2CDF /* StyleCache.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StyleCache.swift; sourceTree = "<group>"; };
@@ -369,6 +372,7 @@
 				7EB914CF2ADC11F4004B3435 /* NotificationPresenter.swift */,
 				7EF32BB02B10167B000E7CAE /* NotificationPresenterLegacyOverlay.swift */,
 				28D81AA62B0140C100DE2CDF /* NotificationStyle.swift */,
+				2884CABF2D04DCA5005E00A6 /* NotificationViewExtension.swift */,
 			);
 			path = Public;
 			sourceTree = "<group>";
@@ -741,6 +745,7 @@
 				28D81A942B010C7500DE2CDF /* DiscoveryHelper.swift in Sources */,
 				28D81A9B2B01217100DE2CDF /* NotificationWindow.swift in Sources */,
 				7E2A4E852AE70A4B001F0DB0 /* NotificationPresenter.swift in Sources */,
+				2884CAC12D04DCA5005E00A6 /* NotificationViewExtension.swift in Sources */,
 				28D81AA72B0140C100DE2CDF /* NotificationStyle.swift in Sources */,
 				7E5402C6286708850079C579 /* JDStatusBarNotification.docc in Sources */,
 			);
@@ -793,6 +798,7 @@
 				28D81A9C2B01217100DE2CDF /* NotificationWindow.swift in Sources */,
 				7EDAEE972AF6EC5E001B6ABE /* NotificationPresenter.swift in Sources */,
 				28D81A952B0110C700DE2CDF /* DiscoveryHelper.swift in Sources */,
+				2884CAC02D04DCA5005E00A6 /* NotificationViewExtension.swift in Sources */,
 				28D81AA82B0140C100DE2CDF /* NotificationStyle.swift in Sources */,
 				7EDAEEA22AF6EC5E001B6ABE /* JDStatusBarNotification.docc in Sources */,
 			);

JDStatusBarNotification/Private/NotificationViewController.swift

@@ -9,8 +9,9 @@
 import Foundation
 import UIKit
 
-protocol NotificationViewControllerDelegate: NSObject {
-  func didDismissStatusBar()
+protocol NotificationPresentationDelegate: NSObject {
+  func didPresentNotification()
+  func didDismissNotification()
 }
 
 class NotificationViewController: UIViewController, NotificationViewDelegate {
@@ -24,7 +25,7 @@ class NotificationViewController: UIViewController, NotificationViewDelegate {
   private var panMaxY: CGFloat = 0.0
 
   private(set) var statusBarView: NotificationView
-  weak var delegate: NotificationViewControllerDelegate?
+  weak var delegate: NotificationPresentationDelegate?
   weak var jdsb_window: UIWindow?
 
   init() {
@@ -71,7 +72,10 @@ class NotificationViewController: UIViewController, NotificationViewDelegate {
     dismissCompletionBlock = nil
 
     // animate in
-    animator.animateIn(for: 0.4, completion: completion)
+    animator.animateIn(for: 0.4) { [weak self] in
+      self?.delegate?.didPresentNotification()
+      completion?()
+    }
 
     return view
   }
@@ -215,7 +219,7 @@ class NotificationViewController: UIViewController, NotificationViewDelegate {
 
       // Animate out
       animator.animateOut(for: duration) { [weak self] in
-        self?.delegate?.didDismissStatusBar()
+        self?.delegate?.didDismissNotification()
         completion?()
       }
     } else {

JDStatusBarNotification/Private/NotificationWindow.swift

@@ -9,16 +9,11 @@
 import Foundation
 import UIKit
 
-protocol NotificationWindowDelegate : AnyObject {
-  func didDismissStatusBar()
-}
-
-class NotificationWindow: UIWindow, NotificationViewControllerDelegate {
+class NotificationWindow: UIWindow {
   let statusBarViewController: NotificationViewController
-  weak var delegate: NotificationWindowDelegate?
 
   init(windowScene: UIWindowScene?,
-       delegate: NotificationWindowDelegate)
+       delegate: NotificationPresentationDelegate)
   {
 
     let statusBarViewController = NotificationViewController()
@@ -36,8 +31,7 @@ class NotificationWindow: UIWindow, NotificationViewControllerDelegate {
       super.init(frame: UIScreen.main.bounds)
     }
 
-    self.delegate = delegate
-    statusBarViewController.delegate = self
+    statusBarViewController.delegate = delegate
     statusBarViewController.jdsb_window = self
     rootViewController = statusBarViewController
 
@@ -51,12 +45,6 @@ class NotificationWindow: UIWindow, NotificationViewControllerDelegate {
     fatalError("init(coder:) has not been implemented")
   }
 
-  // MARK: - NotificationViewControllerDelegate
-
-  func didDismissStatusBar() {
-    delegate?.didDismissStatusBar()
-  }
-
   // MARK: - HitTest
 
   public override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {

JDStatusBarNotification/Public/NotificationPresenter.swift

@@ -23,21 +23,29 @@ import SwiftUI
  * added by the user also stay in memory permanently.
  */
 @objc(JDStatusBarNotificationPresenter)
-public class NotificationPresenter: NSObject, NotificationWindowDelegate {
+public class NotificationPresenter: NSObject {
 
   var overlayWindow: NotificationWindow?
-  var styleCache: StyleCache
+  var windowScene: UIWindowScene?
+  var styleCache = StyleCache()
 
-  /// Provides access to the shared presenter. This is the entry point to present, style and dismiss notifications.
-  ///
-  /// - Returns: An initialized ``NotificationPresenter`` instance.
-  @objc(sharedPresenter)
-  public private(set) static var shared = NotificationPresenter()
+  // swiftui-alert-style presentation state
+  var activeNotificationId: UUID? = nil
+  var didPresentNotificationClosure: ((NotificationPresenter) -> Void)? = nil
+  var didDismissNotificationClosure: ((NotificationPresenter) -> Void)? = nil
 
-  private override init() {
-    styleCache = StyleCache()
+  var statusBarView: NotificationView? {
+    return overlayWindow?.statusBarViewController.statusBarView
   }
 
+  // keep init private to this file
+  private override init() {}
+}
+
+// MARK: - Core Logic
+
+extension NotificationPresenter : NotificationPresentationDelegate {
+
   /// Called upon animation completion.
   ///
   /// - Parameter presenter: Provides the shared ``NotificationPresenter`` instance. That simplifies any subsequent calls to it upon completion.
@@ -56,6 +64,8 @@ public class NotificationPresenter: NSObject, NotificationWindowDelegate {
                            subtitle: String? = nil,
                            style: StatusBarNotificationStyle,
                            completion: Completion? = nil) -> NotificationView {
+    activeNotificationId = UUID()
+
     let window = overlayWindow ?? NotificationWindow(windowScene: windowScene, delegate: self)
     overlayWindow = window
 
@@ -72,16 +82,32 @@ public class NotificationPresenter: NSObject, NotificationWindowDelegate {
     return view
   }
 
-  // MARK: - NotificationWindowDelegate
+  // MARK: - NotificationPresentationDelegate
 
-  func didDismissStatusBar() {
+  func didPresentNotification() {
+    didPresentNotificationClosure?(self)
+  }
+
+  func didDismissNotification() {
     overlayWindow?.removeFromSuperview()
     overlayWindow?.isHidden = true
     overlayWindow?.rootViewController = nil
     overlayWindow = nil
+
+    activeNotificationId = nil
+    didDismissNotificationClosure?(self)
   }
+}
+
+// MARK: - Public API
 
-  // MARK: - Public API
+extension NotificationPresenter {
+
+  /// Provides access to the shared presenter. This is the entry point to present, style and dismiss notifications.
+  ///
+  /// - Returns: An initialized ``NotificationPresenter`` instance.
+  @objc(sharedPresenter)
+  public private(set) static var shared = NotificationPresenter()
 
   // MARK: - Presentation
 
@@ -336,13 +362,6 @@ public class NotificationPresenter: NSObject, NotificationWindowDelegate {
   public func setWindowScene(_ windowScene: UIWindowScene?) {
     self.windowScene = windowScene
   }
-  private var windowScene: UIWindowScene?
-
-  // MARK: - Private
-
-  private var statusBarView: NotificationView? {
-    return overlayWindow?.statusBarViewController.statusBarView
-  }
 }
 
 // MARK: - HostingControllerSizingController

JDStatusBarNotification/Public/NotificationViewExtension.swift

@@ -0,0 +1,60 @@
+//
+//  NotificationViewExtension.swift
+//  JDStatusBarNotification
+//
+//  Created by Markus on 12/7/24.
+//  Copyright © 2024 Markus. All rights reserved.
+//
+
+import SwiftUI
+
+private struct SwiftUINotficationState {
+  static var notificationId: UUID? = nil
+}
+
+extension View {
+  public typealias NotificationPrepareStyleClosure = (StatusBarNotificationStyle) -> Void
+
+  nonisolated public func notification(isPresented: Binding<Bool>, style: NotificationPrepareStyleClosure? = nil, @ViewBuilder viewBuilder: () -> some View) -> some View {
+    let np = NotificationPresenter.shared
+
+    // dismiss if needed
+    if !isPresented.wrappedValue && np.isVisible && np.activeNotificationId == SwiftUINotficationState.notificationId {
+      np.dismiss(animated: true)
+    }
+
+    // present if needed
+    if isPresented.wrappedValue && SwiftUINotficationState.notificationId == nil {
+      if let style {
+        let name = np.addStyle(named: "__swiftui-extension-style") { s in
+          let _ = style(s)
+          return s
+        }
+        np.presentSwiftView(styleName: name, viewBuilder: viewBuilder)
+      } else {
+        np.presentSwiftView(viewBuilder: viewBuilder)
+      }
+
+      // remember id of our presentation
+      SwiftUINotficationState.notificationId = np.activeNotificationId
+
+      // setup callback to react to other calls replacing this presentation
+      np.didPresentNotificationClosure = {
+        if $0.activeNotificationId != SwiftUINotficationState.notificationId {
+          isPresented.wrappedValue = false
+          SwiftUINotficationState.notificationId = nil
+        }
+      }
+
+      // reset state on dismissal
+      np.didDismissNotificationClosure = {
+        $0.didPresentNotificationClosure = nil
+        $0.didDismissNotificationClosure = nil
+        SwiftUINotficationState.notificationId = nil
+        isPresented.wrappedValue = false
+      }
+    }
+
+    return self
+  }
+}