[Messaging] Fix deprecated UNNotificationPresentationOptions (#1784)

messaging/MessagingExample/AppDelegate.m

@@ -122,7 +122,15 @@ - (void)userNotificationCenter:(UNUserNotificationCenter *)center
   NSLog(@"%@", userInfo);
 
   // Change this to your preferred presentation option
-  completionHandler(UNNotificationPresentationOptionBadge | UNNotificationPresentationOptionAlert);
+  // Note: UNNotificationPresentationOptionAlert has been deprecated.
+  if (@available(iOS 14.0, *)) {
+    completionHandler(UNNotificationPresentationOptionList |
+                      UNNotificationPresentationOptionBanner |
+                      UNNotificationPresentationOptionSound);
+  } else {
+    completionHandler(UNNotificationPresentationOptionAlert |
+                      UNNotificationPresentationOptionSound);
+  }
 }
 
 // Handle notification messages after display notification is tapped by the user.

messaging/MessagingExampleSwift/AppDelegate.swift

@@ -119,8 +119,13 @@ extension AppDelegate: UNUserNotificationCenterDelegate {
     print(userInfo)
 
     // Change this to your preferred presentation option
-    return [[.alert, .sound]]
-  }
+    // Note: UNNotificationPresentationOptions.alert has been deprecated.
+    if #available(iOS 14.0, *) {
+      return [.list, .banner, .sound]
+    } else {
+      return [.alert, .sound]
+    }
+}
 
   func userNotificationCenter(_ center: UNUserNotificationCenter,
                               didReceive response: UNNotificationResponse) async {