Show alert on UI XF

showalert.cs

public static class PageExtensions
{
    public static Task<bool> DisplayAlertOnUi(this Page source, string title, string message, string accept, string cancel)
    {
        TaskCompletionSource<bool> doneSource = new TaskCompletionSource<bool>();
        Device.BeginInvokeOnMainThread(async () =>
        {
            try
            {
                var result = await source.DisplayAlert(title, message, accept, cancel);
                doneSource.SetResult(result);
            }
            catch (Exception ex)
            {
                doneSource.SetException(ex);
            }
        });

        return doneSource.Task;
    }
}