Xamarin AlarmManager not firing when app sleeps

问题

I have following code to fire an alarm at exact time. When my app goes to sleep/background, Alarm does not FIRE, however as soon as I unlock my phone, then it fires right away.

    Intent i = new Intent(this, typeof(MyReceiver));
    i.PutExtra("Speaker", txtSpeaker.Text);
    PendingIntent pi = PendingIntent.GetBroadcast(this, 0, i, 0);

    string _date = DateTime.Today.ToString("MM-dd-yyyy")  ;
    string _time = tpick.Hour + ":" + tpick.Minute;
    DateTime scheduleAt = Convert.ToDateTime(_date).Add(TimeSpan.Parse(_time));
    DateTimeOffset dateOffsetValue = DateTimeOffset.Parse(scheduleAt.ToString());
    var millisec = dateOffsetValue.ToUnixTimeMilliseconds();

    AlarmManager alarmManager = (AlarmManager)GetSystemService(AlarmService);
    alarmManager.SetExact(AlarmType.RtcWakeup, millisec, pi);

and here is my Receiver Class...

[BroadcastReceiver]
public class MyReceiver : BroadcastReceiver
{
    public async override void OnReceive(Context context, Intent intent)
    {


        Console.WriteLine("FIRED");

        String result = intent.Extras.GetString("Speaker");

        Toast.MakeText(context, "Alarm Ringing!", ToastLength.Short).Show();

    }
}

回答1:

If the App is running on API 23 or newer, you might want to look into using the SetExactAndAllowWhileIdle method. According to the documentation it appears to me that this method will ignore whether the Device is in some low-power state or doze is enabled.

来源：https://stackoverflow.com/questions/64635627/xamarin-alarmmanager-not-firing-when-app-sleeps