private void TeamAddBtn_Clicked(object sender, EventArgs e)
{
bool isNotHave = true;
foreach (var item in dao.GetTeamUser())
{
if (item.Equals(teamEntry.Text))
{
isNotHave = false;
break;
}
}
if (isNotHave)
{
dao.AddTeam(teamEntry.Text);
}
this.OnAppearing();
}