Question

I am currently trying to port a .Net app to Objective C and Cocoa. I know the basics and have had little trouble with most things. But I’m having trouble retrieving data from the Web.

In C# I would use POST and GET to retrieve information from a server as such

byte[] buffer = Encoding.ASCII.GetBytes("someData");

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("url");
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = buffer.Length;

Stream postData = request.GetRequestStream();
postData.Write(buffer, 0, buffer.Length);
postData.Close();

HttpWebResponse response = (HttpWebResponse)request.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream());

while (!reader.EndOfStream)
{
   String data = read.ReadLine();
   //Do something such as an update on each line read in
}

reader.Close();
response.Close(); 

but I’m not having much luck finding a Cocoa equivelant. I have seen the use of things such as NSUrlDownload but all the examples I can find always show the download of the data as a single blocking function call. Where what I need is to be able to update things as I recieve data, not just wait for it all to arrive then deal with it. And ideally I would be able to deal with different types of data such as text or binary, so I need something similar to a stream that I can pass to a parser of some kind.

So my question is what is the equivelant of the C# code above?

Answer 1

You need to use NSURLConnection and assign an object as its delegate. As the connection receives data, it will call the -connection:didReceiveData: delegate method which you can use to process the incoming data as necessary.

You will need to build the HTTP POST request yourself. I have posted some code that shows how to do this in my answer to this question.