async public void OnPickerSelectedIndexChanged(object sender, EventArgs e)
{
int selectedIndex = FilierPicker.SelectedIndex;
if (selectedIndex != -1)
{
var FilierName = FilierPicker.Items[selectedIndex];
var id = DcFilier[FilierName];
DcLesson = new Dictionary <string, int>();
var NameList = new List <string>();
var LessonVar = await dataLesson.GetLessonNameByFilier(id);
foreach (Lesson Data in LessonVar)
{
DcLesson.Add(Data.LessonName, Data.IdLesson);
NameList.Add(Data.LessonName);
}
LessonPicker.ItemsSource = NameList;
}
}