Xamarin-CrossDownloadManager - waiting for download file - xamarin

Question

I use Xamarin-CrossDownloadManager (https://github.com/SimonSimCity/Xamarin-CrossDownloadManager) and I need waiting for download a file. I have this code:
private static async Task<bool> FileDownloadedTest(string LinkToFile, string PathFile)
{
var downloadManager = CrossDownloadManager.Current;
CrossDownloadManager.Current.PathNameForDownloadedFile = new System.Func<IDownloadFile, string>(file => {
return PathFile;
});
{
await DeleteFile(PathFile);
var file = downloadManager.CreateDownloadFile(LinkToFile);
await Task.Run(() => downloadManager.Start(file, true)); //why this not wait???
}
bool FileExist = await IsFileExist(PathFile);
return FileExist;
}
Why it not wait for finish download action? How to do it?
On library site they wrote, that I can watch the IDownloadManager.Queue to get information when the file is downloaded. But, I don't know how to use this in my method... Can you help me?
PS: Sorry for my english, I'm still learning it ;)

Answer 1

With that library, there is no callback or event published for when a file is finished downloading, but you can do a simple check and wait some more loop.
await Task.Run(async () =>
{
var downloadManager = CrossDownloadManager.Current;
var file = downloadManager.CreateDownloadFile(someFileBasedUrl);
downloadManager.Start(file);
bool isDownloading = true;
while (isDownloading)
{
await Task.Delay(10 * 1000);
isDownloading = IsDownloading(file);
}
});
The IsDownloading method:
bool IsDownloading(IDownloadFile file)
{
if (file == null) return false;
switch (file.Status)
{
case DownloadFileStatus.INITIALIZED:
case DownloadFileStatus.PAUSED:
case DownloadFileStatus.PENDING:
case DownloadFileStatus.RUNNING:
return true;
case DownloadFileStatus.COMPLETED:
case DownloadFileStatus.CANCELED:
case DownloadFileStatus.FAILED:
return false;
default:
throw new ArgumentOutOfRangeException();
}
}
Re: https://github.com/SimonSimCity/Xamarin-CrossDownloadManager/blob/develop/Sample/DownloadExample/Downloader.cs#L46

Answer 2

I don't know why IDownloadFile.Status = COMPLETED not working, but i found solve problem:
await Task.Run(() =>
{
var downloadManager = CrossDownloadManager.Current;
var file = downloadManager.CreateDownloadFile(LinkToFile);
downloadManager.Start(file);
while (file.Status == DownloadFileStatus.INITIALIZED)
{
while (file.TotalBytesExpected > file.TotalBytesWritten)
{
Debug.WriteLine(file.Status);
}
}
});
Somebody know why DownloadFileStatus.INITIALIZED working, but DownloadFileStatus.COMPLETED not?

Answer 3

SushiHangover's answer above worked great, and I combined it with ACR User Dialog's package (https://github.com/aritchie/userdialogs) to show a nice loading progress screen to the user while waiting for the download to complete. This works nicely on Android (I couldn't test iOS yet).
...
var downloadManager = CrossDownloadManager.Current;
var fileToDownload = downloadManager.CreateDownloadFile(args.Url);
downloadManager.Start(fileToDownload, true);
args.Cancel = true;
UserDialogs.Instance.Progress("Downloading").Show();
bool isDownloading = true;
while (isDownloading)
{
await Task.Delay(100);
if (fileToDownload.TotalBytesExpected > 0)
{
UserDialogs.Instance.Progress().PercentComplete = (int)(fileToDownload.TotalBytesWritten / fileToDownload.TotalBytesExpected * 100);
Console.WriteLine(("DOWNLOAD PROGRESS: " + fileToDownload.TotalBytesWritten / fileToDownload.TotalBytesExpected * 100).ToString() + "%");
}
isDownloading = IsDownloading(fileToDownload);
}
UserDialogs.Instance.Progress().Hide();
//Below code opens the download location after download has completed.
Intent intent = new Intent(DownloadManager.ActionViewDownloads);
intent.AddFlags(ActivityFlags.NewTask);
Android.App.Application.Context.StartActivity(intent);
return;
}
}
}
bool IsDownloading(IDownloadFile file)
{
if (file == null) return false;
switch (file.Status)
{
case DownloadFileStatus.INITIALIZED:
case DownloadFileStatus.PAUSED:
case DownloadFileStatus.PENDING:
case DownloadFileStatus.RUNNING:
return true;
case DownloadFileStatus.COMPLETED:
case DownloadFileStatus.CANCELED:
case DownloadFileStatus.FAILED:
return false;
default:
throw new ArgumentOutOfRangeException();
}
}