public async Task <int> DownloadHomepageAsync()
{
try
{
var httpClient = new HttpClient(); // Xamarin supports HttpClient!
//
// download HTML string
Task <string> contentsTask = httpClient.GetStringAsync("http://xamarin.com"); // async method!
ResultTextView.Text += "DownloadHomepage method continues after Async() call, until await is used\n";
// await! control returns to the caller and the task continues to run on another thread
string contents = await contentsTask;
// After contentTask completes, you can calculate the length of the string.
int length = contents.Length;
ResultTextView.Text += "Downloaded the html and found out the length.\n\n";
//
// download image bytes
ResultTextView.Text += "Start downloading image.\n";
byte[] imageBytes = await httpClient.GetByteArrayAsync("http://img.gawkerassets.com/img/196gi7ybcdtk0jpg/original.jpg"); // async method!
ResultTextView.Text += "Downloaded the image.\n";
await SaveBytesToFileAsync(imageBytes, "original.jpg");
DownloadedImageView.Image = UIImage.FromFile(localPath);
//
// byte[] docxBytes = await httpClient.GetByteArrayAsync("http://etkintrafik.com/text.docx"); // async method!
// ResultTextView.Text += " döküman indi.\n";
// await SaveBytesToFileAsync(docxBytes, "text.docx");
//
byte[] xmlBytes = await httpClient.GetByteArrayAsync("http://mobelsis.net/mobelsis.xml"); // async method!
ResultTextView.Text += " döküman indi.\n";
await SaveBytesToFileAsync(xmlBytes, "mobelsis.xml");
ResultTextView.Text += localPath.ToString();
//
//
// save image to Photo Album using async-ified iOS API
ALAssetsLibrary library = new ALAssetsLibrary();
var dict = new NSDictionary();
var assetUrl = await library.WriteImageToSavedPhotosAlbumAsync(DownloadedImageView.Image.CGImage, dict);
ResultTextView.Text += "Saved to album assetUrl = " + assetUrl + "\n";
//
// download multiple images
// http://blogs.msdn.com/b/pfxteam/archive/2012/08/02/processing-tasks-as-they-complete.aspx
Task <byte[]> task1 = httpClient.GetByteArrayAsync("http://xamarin.com/images/tour/amazing-ide.png"); // async method!
Task <byte[]> task2 = httpClient.GetByteArrayAsync("http://xamarin.com/images/how-it-works/chalkboard2.jpg"); // async method!
Task <byte[]> task3 = httpClient.GetByteArrayAsync("http://cdn1.xamarin.com/webimages/images/features/shared-code-2.pngXXX"); // ERROR async method!
List <Task <byte[]> > tasks = new List <Task <byte[]> >();
tasks.Add(task1);
tasks.Add(task2);
tasks.Add(task3);
while (tasks.Count > 0)
{
var t = await Task.WhenAny(tasks);
tasks.Remove(t);
try
{
await t;
ResultTextView.Text += "** Downloaded " + t.Result.Length + " bytes\n";
}
catch (OperationCanceledException)
{
}
catch (Exception exc)
{
ResultTextView.Text += "-- Download ERROR: " + exc.Message + "\n";
}
}
// this doesn't happen until the image has downloaded as well
ResultTextView.Text += "\n\n\n" + contents; // just dump the entire HTML
return(length); // Task<TResult> returns an object of type TResult, in this case int
}
catch (Exception ex)
{
Console.WriteLine("Centralized exception handling!");
return(-1);
}
}
