I access a website and retrieve some data using HttpWebRequest and I need a UIAlertView with a UIActivityIndicatorView to display while it retrieves said data. However, it just dims the screen and doesn't show the alert until it's too late. I've read other threading related questions here and can't figure out how to resolve this. I tried using ThreadPool, InvokeOnMainThread, Tasks, all of which have not worked.
EDIT:
HttpWebRequest url = (HttpWebRequest)WebRequest.Create ("maps.googleapis.com/maps/api/place/search/..);
HttpWebResponse webResp = (HttpWebResponse)url.GetResponse (); JsonValue jVal =
JsonObject.Load (webResp.GetResponseStream ());
JsonObject jObj = (JsonObject)jVal;
I have the above code, if it will properly format for me, how would I convert that to use WebClient? Can you still get JSON and such from it?
It's often a lot easier (and less error prone) to use WebClient and one of it's *Async methods than using HttpWebRequest.
Here's an example to download and show a small image.
WebClient client = new WebClient ();
var wait = new UIActivityIndicatorView (View.Bounds);
client.DownloadDataCompleted += (object sender, DownloadDataCompletedEventArgs e) => {
byte[] result = e.Result;
if (result != null) {
NSData data = NSData.FromArray (e.Result);
UIImage img = UIImage.LoadFromData (data);
InvokeOnMainThread (delegate {
ShowImage (img);
wait.StopAnimating ();
});
}
};
wait.StartAnimating ();
client.DownloadDataAsync (new Uri (url));
EDIT (for updated question)
For streams you can use WebClient.OpenReadAsync and the OpenReadCompleted event.
Related
I have made a REST API and I want to use it using my Xamarin.iOS application.
Basically I want to call the API from my Xamarin application by sending some arguments to one of my API's function.
I tried the resources available at Xamarin's official website, but I a newbie so I cannot understand how it was done.
The REST API is hosted locally by the network I am using. It is not hosted at a static IP.
Kindly guide me.
You don't really need a fancy plugin if you just want to hit Web Endpoints. I simply use the basic WebRequest API.
var request = WebRequest.CreateHttp(YOUR_URL_HERE);
request.Method = "GET";
request.ContentType = "application/JSON";
request.BeginGetResponse(ResponseComplete, request);
... and then your response method can be something along the lines of...
protected void ResponseComplete(IAsyncResult result)
{
try
{
var request = result.AsyncState as HttpWebRequest;
if (request != null)
{
Debug.WriteLine("Completed query: " + request.RequestUri);
using (var streamReader = new StreamReader(response.GetResponseStream()))
{
var result = streamReader.ReadToEnd();
Debug.WriteLine("Query Result: " + result);
}
}
}
}
... and if you need to post data you can add request.BeginGetRequestStream(PostData, request); before request.BeginGetResponse(ResponseComplete, request); and make your GetRequestStream handling method something along the lines of...
protected void PostData(IAsyncResult result)
{
var request = result.AsyncState as HttpWebRequest;
if (request != null)
{
using (var postStream = request.EndGetRequestStream(result))
{
var json = JsonConvert.SerializeObject(DATA_TO_POST);
Debug.WriteLine("Posting data: " + json);
var byteArray = Encoding.UTF8.GetBytes(json);
postStream.Write(byteArray, 0, byteArray.Length);
}
}
}
I would recommend Refit, you can install it as a NuGet package. Its pritty simple to use.
Refit allows us to define an interface that describes the API that we're calling, and the Refit framework handles making the call to the service and deserializing the return.
Have a look at this great blog post on how to set it up and other packages that might help you out. http://arteksoftware.com/resilient-network-services-with-xamarin/
I have used RestSharp before but Refit is alot easier to get running.
I'm using the twitter4j library to access the public twitter stream. I'm trying to make a project involving geotagged tweets, and I need to collect a large number of them for testing.
Right now I am getting the unfiltered stream from twitter and only saving tweets with geotags. This is slow though because the VAST majority of tweets don't have geo tags. I want the twitter stream to send me only tweets with geotags.
I have tried using the method mentioned in [this question][1], where you filter with a bounding box of size 360* by 180* but that's not working for me. I'm not getting any errors when using that filter, but I'm still getting 99% of tweets with no geotags. Here is how I'm doing it:
DefaultHttpClient httpclient = new DefaultHttpClient();
httpclient.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
new DefaultHttpMethodRetryHandler());
HttpGet httpget = new HttpGet("https://developers.facebook.com/docs/reference/api/examples/");
HttpResponse response = httpclient.execute(httpget);
HttpEntity entity = response.getEntity();
if (entity != null) {
entity.consumeContent();
}
List<Cookie> cookies = httpclient.getCookieStore().getCookies();
HttpPost httpost = new HttpPost(
"https://www.facebook.com/login.php?login_attempt=1");
List<NameValuePair> nvps = new ArrayList<NameValuePair>();
nvps.add(new BasicNameValuePair("email", "xxxxxxxxxxxxxx"));
nvps.add(new BasicNameValuePair("pass", "ssssssss"));
httpost.setEntity(new UrlEncodedFormEntity(nvps, HTTP.UTF_8));
response = httpclient.execute(httpost);
entity = response.getEntity();
if (entity != null) {
entity.consumeContent();
}
CookieStore cookiestrore = httpclient.getCookieStore();
//cookies = httpclient.getCookieStore().getCookies();
//httpclient.getConnectionManager().shutdown();
return cookiestrore;
Any this is not getting any error but i am not getting any results.
When you track keyword it is separate job from tracking locations. These are logical ORs
I am using MonoTouch to build an iPhone app. In the app I am making Web Requests to pull back information from the web services running on our server.
This is my method to build the request:
public static HttpWebRequest CreateRequest(string serviceUrl, string methodName, JsonObject methodArgs)
{
string body = "";
body = methodArgs.ToString();
HttpWebRequest request = WebRequest.Create(serviceUrl) as HttpWebRequest;
request.ContentLength = body.Length; // Set type to POST
request.Method = "POST";
request.ContentType = "text/json";
request.Headers.Add("X-JSON-RPC", methodName);
StreamWriter strm = new StreamWriter(request.GetRequestStream(), System.Text.Encoding.ASCII);
strm.Write(body);
strm.Close();
return request;
}
Then I call it like this:
var request = CreateRequest(URL, METHOD_NAME, args);
request.BeginGetResponse (new AsyncCallback(ProcessResponse), request);
And ProcessResponse looks like this:
private void ProcessResponse(IAsyncResult result)
{
try
{
HttpWebRequest request = (HttpWebRequest)result.AsyncState;
using (HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(result)) // this is where the exception gets thrown
{
using (StreamReader strm = new System.IO.StreamReader(response.GetResponseStream()))
{
JsonValue value = JsonObject.Load(strm);
// do stuff...
strm.Close();
} // using
response.Close();
} // using
Busy = false;
}
catch(Exception e)
{
Console.Error.WriteLine (e.Message);
}
}
There is another question about this issue for Monodroid and the answer there suggested explicitly closing the output stream. I tried this but it doesn't solve the problem. I am still getting a lot of ReadDone2 errors occurring.
My workaround at the moment involves just re-submitting the Web Request if an error occurs and the second attempt seems to work in most cases. These errors only happen when I am testing on the phone itself and never occur when using the Simulator.
Whenever possible try to use WebClient since it will deal automatically with a lot of details (including streams). It also makes it easier to make your request async which is often helpful for not blocking the UI.
E.g. WebClient.UploadDataAsync looks like a good replacement for the above. You will get the data, when received from the UploadDataCompleted event (sample here).
Also are you sure your request is always and only using System.Text.Encoding.ASCII ? using System.Text.Encoding.UTF8 is often usedm, by default, since it will represent more characters.
UPDATE: If you send or receive large amount to byte[] (or string) then you should look at using OpenWriteAsync method and OpenWriteCompleted event.
This is a bug in Mono, please see https://bugzilla.xamarin.com/show_bug.cgi?id=19673
this is what I have so far:
void xmppConnection_OnReadXml(object sender, string xml)
{
if (xml.Contains(XmlTags.PhotoOpen))
{
int startIndex = xml.IndexOf(XmlTags.PhotoOpen) + XmlTags.PhotoOpen.Length;
int length = xml.IndexOf(XmlTags.PhotoClose) - startIndex;
string photoHash = xml.Substring(startIndex, length);
}
}
I guess I can't undo the hash, but I want to the get a person's avatar/photo. How do I achieve this?
You need to handle the VCard events and responses from XMPP connection:
private void vcardToolStripMenuItem_Click(object sender, EventArgs e)
{
RosterNode node = rosterControl.SelectedItem();
if (node != null)
{
frmVcard f = new frmVcard(node.RosterItem.Jid, XmppCon);
f.Show();
}
}
The above is from the miniclient solution example from the AGSXMPP download. Note, it happens when a user request a VCARD for a user. You can initiate that request whenever you want, however.
private void VcardResult(object sender, IQ iq, object data)
{
if (InvokeRequired)
{
// Windows Forms are not Thread Safe, we need to invoke this :(
// We're not in the UI thread, so we need to call BeginInvoke
BeginInvoke(new IqCB(VcardResult), new object[] { sender, iq, data });
return;
}
if (iq.Type == IqType.result)
{
Vcard vcard = iq.Vcard;
if (vcard!=null)
{
txtFullname.Text = vcard.Fullname;
txtNickname.Text = vcard.Nickname;
txtBirthday.Text = vcard.Birthday.ToString();
txtDescription.Text = vcard.Description;
Photo photo = vcard.Photo;
if (photo != null)
picPhoto.Image = vcard.Photo.Image;
}
}
}
That is what happens when someone requests the VCARD information from XMPP and the IQ type matches the proper data. You can thenpull the photo from vcard.Photo.
You trigger the pull with:
VcardIq viq = new VcardIq(IqType.get, new Jid(jid.Bare));
con.IqGrabber.SendIq(viq, new IqCB(VcardResult), null);
The first line there is the request to the XMPP server, that the VCARD form uses to request user information.
The second line there, sets up another grabber (callback of sorts), that the form uses to wait for the information to arrive, and then parse out the necessary information. IN this case, the grabber is in a new form, so that the main application doesn't have to worry about parsing that information.
You can look at the entire source by extracting the AGSXMPP zip file to your local drive, and looking in the Samples\VS2008\miniclient folder.
You can click link:http://forum.ag-software.de/thread/192-How-to-save-vcard-data
I am trying to download HTML content from any URL through webbrowser control in C#.net.
I choose webrowser to handle Javascript issues. I am using webbrowser control without placing
it on the form. It works great for one url, but when I call it for multiple urls I am unable
to download the page.
Here is the code
GetWebpage()
{
System.Windows.Forms.WebBrowser wb = new System.Windows.Forms.WebBrowser();
wb.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(wb_DocumentCompleted);
wb.Navigate(sURI, false);
bDocumentLoaded = false;
while (!bDocumentLoaded)
{
Application.DoEvents();
Thread.Sleep(100);
}
sHTML = wb.DocumentText;
bDocumentLoaded = false;
}
Event:
private void wb_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
System.Windows.Forms.WebBrowser webBrowser1;
webBrowser1 = sender as WebBrowser;
string strTit = webBrowser1.DocumentTitle;
string str = webBrowser1.DocumentText;
bDocumentLoaded = true;
}
Cheers,
Karthik
You can use webclient object to fetch data from some url.
Try using Downloading String
public static void DownloadString (string address)
{
WebClient client = new WebClient ();
string reply = client.DownloadString (address);
Console.WriteLine (reply);
}
You can also use ASYC method of same downloading string.
I think your problem is that some sites are detecting specific browsertype and then they are returning HTML
Try setting the HeaderProperty of WebClient Object this is a list of HttpWebRequest Object
For Example
myWebClient.Headers.Add("Content-Type","application/x-www-form-urlencoded");
Modify the useragent of HTTPWEBRequest then add to headers.
HTTPWEBRequest.UserAgent=".NET Framework Test Client";
You can check more information about this in MSDN Link
I might recommend using the mshtml and SHDocVW libraries and using approach found in the answer here:
Unable to to locate and click a submit button using mshtml.HTMLInputElement