MainActivity.cs

using Android.App;
using Android.Content;
using Android.Content.PM;
using Android.OS;
using Android.Runtime;
using Android.Util;
using Xamarin.Forms;

namespace RoosterBlock.Droid
{
    // TODO: The SingleTop mode prevents multiple instances of an Activity from being started while the application is in the foreground. This LaunchMode may
    // not be appropriate for applications that launch multiple activities in more complex notification scenarios. For more information about LaunchMode
    // enumeration values, see Android Activity LaunchMode.  *** The LaunchMode.SingleTop may not be the right mode for this app. ***
    // https://developer.android.com/guide/topics/manifest/activity-element#lmode
    [Activity(
        Label = "Rooster Block",
        Icon = "@mipmap/icon",
        Theme = "@style/MainTheme",
        MainLauncher = true,
        ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize,
        LaunchMode = LaunchMode.SingleTop)]
    public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
    {
        MMSReceiver mmsReceiver;
        SMSReceiver smsReceiver;

        protected override void OnCreate(Bundle savedInstanceState)
        {
            TabLayoutResource = Resource.Layout.Tabbar;
            ToolbarResource = Resource.Layout.Toolbar;

            base.OnCreate(savedInstanceState);

            mmsReceiver = new MMSReceiver();
            smsReceiver = new SMSReceiver();
            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
            LoadApplication(new App());

            Log.Info("MainActivity", "Rob Completed Initialization");
        }

        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
        {
            Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);

            base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
        }

        /// <summary>
        /// If the application is already running in the foreground, the Intent data will be passed to this OnNewIntent
        /// method. Note that when the application is started by notification data, the Intent data will be passed to
        /// the OnCreate method.
        /// </summary>
        /// <param name="intent">This contains the title and message of the notification.</param>
        protected override void OnNewIntent(Intent intent)
        {
            CreateNotificationFromIntent(intent);
        }

        /// <summary>
        /// Create the Android notification when a message is received.
        /// </summary>
        /// <param name="intent">This contains the title and message of the notification.</param>
        public static void CreateNotificationFromIntent(Intent intent)
        {
            // TODO: Android offers many advanced options for notifications. For more information, see Notifications in
            // Xamarin.Android.
            // https://docs.microsoft.com/en-us/xamarin/android/app-fundamentals/notifications/
            if (intent?.Extras != null)
            {
                string title = intent.Extras.GetString(AndroidNotificationManager.TitleKey);
                string message = intent.Extras.GetString(AndroidNotificationManager.MessageKey);
                DependencyService.Get<INotificationManager>().ReceiveNotification(title, message);
            }
        }

        protected override void OnResume()
        {
            base.OnResume();

            IntentFilter smsIntentfilter = new IntentFilter(Android.Provider.Telephony.Sms.Intents.SmsReceivedAction)
            {
                Priority = (int)IntentFilterPriority.HighPriority
            };

            IntentFilter mmsIntentfilter = new IntentFilter(Android.Provider.Telephony.Sms.Intents.WapPushReceivedAction)
            {
                Priority = (int)IntentFilterPriority.HighPriority
            };
            mmsIntentfilter.AddDataType("application/vnd.wap.mms-message");

            RegisterReceiver(smsReceiver, smsIntentfilter);
            RegisterReceiver(mmsReceiver, mmsIntentfilter);
        }

        protected override void OnDestroy()
        {
            UnregisterReceiver(mmsReceiver);
            UnregisterReceiver(smsReceiver);
            base.OnDestroy();
        }
    }
}