From 5e2d0cf8fb7a157876da9f1fa24bc5f32c3a1761 Mon Sep 17 00:00:00 2001
From: David Britch <davidbritch@users.noreply.github.com>
Date: Fri, 12 Feb 2021 16:20:45 +0000
Subject: [PATCH] Backgrounded app updates. (#701)

---
 .../AlarmHandler.cs                           |  3 ++-
 .../AndroidNotificationManager.cs             | 17 +++++++++++--
 .../BootReceiver.cs                           | 19 +++++++++++++++
 .../LocalNotifications.Android.csproj         |  1 +
 .../Properties/AndroidManifest.xml            |  5 ++--
 .../LocalNotifications.iOS/AppDelegate.cs     |  2 +-
 .../iOSNotificationReceiver.cs                | 24 +++++++++++++++----
 7 files changed, 61 insertions(+), 10 deletions(-)
 create mode 100644 LocalNotifications/LocalNotifications/LocalNotifications.Android/BootReceiver.cs

diff --git a/LocalNotifications/LocalNotifications/LocalNotifications.Android/AlarmHandler.cs b/LocalNotifications/LocalNotifications/LocalNotifications.Android/AlarmHandler.cs
index 9f5b4fd67..bee012411 100644
--- a/LocalNotifications/LocalNotifications/LocalNotifications.Android/AlarmHandler.cs
+++ b/LocalNotifications/LocalNotifications/LocalNotifications.Android/AlarmHandler.cs
@@ -12,7 +12,8 @@ namespace LocalNotifications.Droid
                 string title = intent.GetStringExtra(AndroidNotificationManager.TitleKey);
                 string message = intent.GetStringExtra(AndroidNotificationManager.MessageKey);
 
-                AndroidNotificationManager.Instance.Show(title, message);
+                AndroidNotificationManager manager = AndroidNotificationManager.Instance ?? new AndroidNotificationManager();
+                manager.Show(title, message);
             }
         }
     }
diff --git a/LocalNotifications/LocalNotifications/LocalNotifications.Android/AndroidNotificationManager.cs b/LocalNotifications/LocalNotifications/LocalNotifications.Android/AndroidNotificationManager.cs
index 0d7c7beed..cd85c9e46 100644
--- a/LocalNotifications/LocalNotifications/LocalNotifications.Android/AndroidNotificationManager.cs
+++ b/LocalNotifications/LocalNotifications/LocalNotifications.Android/AndroidNotificationManager.cs
@@ -29,10 +29,15 @@ namespace LocalNotifications.Droid
 
         public static AndroidNotificationManager Instance { get; private set; }
 
+        public AndroidNotificationManager() => Initialize();
+
         public void Initialize()
         {
-            CreateNotificationChannel();
-            Instance = this;
+            if (Instance == null)
+            {
+                CreateNotificationChannel();
+                Instance = this;
+            }
         }
 
         public void SendNotification(string title, string message, DateTime? notifyTime = null)
@@ -89,6 +94,14 @@ namespace LocalNotifications.Droid
             manager.Notify(messageId++, notification);
         }
 
+        public void DeleteNotification(int id)
+        {
+            Intent intent = new Intent(AndroidApp.Context, typeof(AlarmHandler));
+            PendingIntent pendingIntent = PendingIntent.GetBroadcast(AndroidApp.Context, id, intent, PendingIntentFlags.CancelCurrent);
+            AlarmManager alarmManager = AndroidApp.Context.GetSystemService(Context.AlarmService) as AlarmManager;
+            alarmManager.Cancel(pendingIntent);
+        }
+
         void CreateNotificationChannel()
         {
             manager = (NotificationManager)AndroidApp.Context.GetSystemService(AndroidApp.NotificationService);
diff --git a/LocalNotifications/LocalNotifications/LocalNotifications.Android/BootReceiver.cs b/LocalNotifications/LocalNotifications/LocalNotifications.Android/BootReceiver.cs
new file mode 100644
index 000000000..ee7f3664c
--- /dev/null
+++ b/LocalNotifications/LocalNotifications/LocalNotifications.Android/BootReceiver.cs
@@ -0,0 +1,19 @@
+using Android.App;
+using Android.Content;
+
+namespace LocalNotifications.Droid
+{
+    [BroadcastReceiver(Enabled = true, Label = "Reboot complete receiver")]
+    [IntentFilter(new[] { Android.Content.Intent.ActionBootCompleted })]
+    public class BootReceiver : BroadcastReceiver
+    {
+        public override void OnReceive(Context context, Intent intent)
+        {
+            if (intent.Action == "android.intent.action.BOOT_COMPLETED")
+            {
+                // Recreate alarms
+            }
+        }
+    }
+}
+
diff --git a/LocalNotifications/LocalNotifications/LocalNotifications.Android/LocalNotifications.Android.csproj b/LocalNotifications/LocalNotifications/LocalNotifications.Android/LocalNotifications.Android.csproj
index f0e38c210..5b824680d 100644
--- a/LocalNotifications/LocalNotifications/LocalNotifications.Android/LocalNotifications.Android.csproj
+++ b/LocalNotifications/LocalNotifications/LocalNotifications.Android/LocalNotifications.Android.csproj
@@ -60,6 +60,7 @@
     <Compile Include="Resources\Resource.designer.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="AlarmHandler.cs" />
+    <Compile Include="BootReceiver.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="Resources\AboutResources.txt" />
diff --git a/LocalNotifications/LocalNotifications/LocalNotifications.Android/Properties/AndroidManifest.xml b/LocalNotifications/LocalNotifications/LocalNotifications.Android/Properties/AndroidManifest.xml
index 9cbaabc55..8896e050a 100644
--- a/LocalNotifications/LocalNotifications/LocalNotifications.Android/Properties/AndroidManifest.xml
+++ b/LocalNotifications/LocalNotifications/LocalNotifications.Android/Properties/AndroidManifest.xml
@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" android:versionName="1.0" package="com.companyname.localnotifications">
-	<uses-sdk android:minSdkVersion="21" android:targetSdkVersion="29" />
+	<uses-sdk android:minSdkVersion="26" android:targetSdkVersion="29" />
 	<application android:label="LocalNotifications.Android"></application>
 	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
-</manifest>
+	<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
+</manifest>
\ No newline at end of file
diff --git a/LocalNotifications/LocalNotifications/LocalNotifications.iOS/AppDelegate.cs b/LocalNotifications/LocalNotifications/LocalNotifications.iOS/AppDelegate.cs
index a59031e92..b928f8189 100644
--- a/LocalNotifications/LocalNotifications/LocalNotifications.iOS/AppDelegate.cs
+++ b/LocalNotifications/LocalNotifications/LocalNotifications.iOS/AppDelegate.cs
@@ -11,7 +11,7 @@ namespace LocalNotifications.iOS
         {
             global::Xamarin.Forms.Forms.Init();
 
-            // set a delegate to handle incoming notifications
+            // Set a delegate to handle incoming notifications.
             UNUserNotificationCenter.Current.Delegate = new iOSNotificationReceiver();
 
             LoadApplication(new App());
diff --git a/LocalNotifications/LocalNotifications/LocalNotifications.iOS/iOSNotificationReceiver.cs b/LocalNotifications/LocalNotifications/LocalNotifications.iOS/iOSNotificationReceiver.cs
index 25aef83ba..4f4689b54 100644
--- a/LocalNotifications/LocalNotifications/LocalNotifications.iOS/iOSNotificationReceiver.cs
+++ b/LocalNotifications/LocalNotifications/LocalNotifications.iOS/iOSNotificationReceiver.cs
@@ -6,13 +6,29 @@ namespace LocalNotifications.iOS
 {
     public class iOSNotificationReceiver : UNUserNotificationCenterDelegate
     {
+        // Called if app is in the foreground.
         public override void WillPresentNotification(UNUserNotificationCenter center, UNNotification notification, Action<UNNotificationPresentationOptions> completionHandler)
         {
-            DependencyService.Get<INotificationManager>().ReceiveNotification(notification.Request.Content.Title, notification.Request.Content.Body);
-
-            // alerts are always shown for demonstration but this can be set to "None"
-            // to avoid showing alerts if the app is in the foreground
+            ProcessNotification(notification);
             completionHandler(UNNotificationPresentationOptions.Alert);
         }
+
+        // Called if app is in the background, or killed state.
+        public override void DidReceiveNotificationResponse(UNUserNotificationCenter center, UNNotificationResponse response, Action completionHandler)
+        {
+            if (response.IsDefaultAction)
+            {
+                ProcessNotification(response.Notification);
+            }
+            completionHandler();
+        }
+
+        void ProcessNotification(UNNotification notification)
+        {
+            string title = notification.Request.Content.Title;
+            string message = notification.Request.Content.Body;
+
+            DependencyService.Get<INotificationManager>().ReceiveNotification(title, message);
+        }
     }
 }
\ No newline at end of file