local Notification with an Alarm Schedulling in Xamarin.Android doesn't work well - notifications

Question

Am trying to make an Alarm notify on a scheduled time from my Sqlite, but the Alarm notifies only when i launch the Application, why is this
Below is how am Implementing my Alarm class:
public class AlarmImplementation
{
public AlarmImplementation()
{
}
public async void MakeAlarm()
{
MedicationDatabase db = new MedicationDatabase();
//This method has the list of time in Sqlite
var alarm_list = db.GetAlarmList();
//Debug.WriteLine(" Time -- : "+ m.ToString());
var message = "Hello Its me new one ";
var title = "Diabetics App";
//looping time from Sqlite
foreach (var list in alarm_list)
{
var hour = Int32.Parse(list.Substring(0, 2));
var minute = Int32.Parse(list.Substring(3, 2));
Debug.WriteLine("Hour : " + hour + "\n");
Debug.WriteLine("Minute " + minute + "\n");
Intent myintent = new Intent(Xamarin.Forms.Forms.Context, typeof(AlarmReceiver));
myintent.PutExtra("message", message);
myintent.PutExtra("title", title);
PendingIntent pendingintent = PendingIntent.GetBroadcast(Xamarin.Forms.Forms.Context, 0, myintent, PendingIntentFlags.UpdateCurrent);
Java.Util.Date date = new Java.Util.Date();
Java.Util.Calendar cal = Java.Util.Calendar.Instance;
cal.TimeInMillis = Java.Lang.JavaSystem.CurrentTimeMillis();
cal.Set(Java.Util.CalendarField.HourOfDay, hour);
cal.Set(Java.Util.CalendarField.Minute, minute);
cal.Set(Java.Util.CalendarField.Second, 0);
// PendingIntent pendingIntent = PendingIntent.GetBroadcast(this, 0, alarmIntent, PendingIntentFlags.UpdateCurrent);
AlarmManager alarmManager = Xamarin.Forms.Forms.Context.GetSystemService(Android.Content.Context.AlarmService) as AlarmManager;
alarmManager.Set(AlarmType.RtcWakeup, cal.TimeInMillis, pendingintent);
}
}
}
Now when you look at my code above , I get time from my Sqlite then
i wire it in the AlarmManager.
Then in the code below i think i call the MakeAlarm Method in the
MainActivity.
This is my MainActivity class:
public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
{
protected override void OnCreate(Bundle bundle)
{
TabLayoutResource = Resource.Layout.Tabbar;
ToolbarResource = Resource.Layout.Toolbar;
// ActionBar.Hide();
RequestWindowFeature(WindowFeatures.NoTitle);
base.OnCreate(bundle);
global::Xamarin.Forms.Forms.Init(this, bundle);
//Xamarin.Forms.Init();
AlarmImplementation a = new AlarmImplementation();
Task startupWork = new Task(() => { a.MakeAlarm(); });
startupWork.Start();
LoadApplication(new App());
}
}
My Question is how can i make an Alarm notify on a scheduled time
without pressing a Button, since i have my time in the Sqlite.