public async Task GetFile()
{
    Windows.Storage.Pickers.FileOpenPicker picker = new Windows.Storage.Pickers.FileOpenPicker();
    picker.ViewMode = Windows.Storage.Pickers.PickerViewMode.List;
    picker.FileTypeFilter.Add(".txt");
    //Prompt the user to open the log file:
    Windows.Storage.StorageFile logFile = await picker.PickSingleFileAsync();

    try
    {
        using (var stream = await logFile.OpenStreamForReadAsync())
        using (var reader = new StreamReader(stream))
        {
            var line = await reader.ReadLineAsync();
            Debug.WriteLine($"The first line: {line} - waiting");
            await Task.Delay(10000);
            line = await reader.ReadLineAsync();
            Debug.WriteLine($"The next line: {line} - waiting");
        }
    }
    catch (Exception exc)
    {
        Debug.WriteLine($"Exception {exc.Message}");
    }
}