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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?

Tristan
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1 Answers1

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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.

Community
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Rob Keniger
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  • Thank you very much that worked worked, If I wanted to use your method to send an array of strings to a php script how would I manage that with the dictionary your using? – Tristan May 06 '10 at 04:16
  • Posting a PHP array is a little difficult because you need multiple values with the same name (`nameOfKey[]`). Obviously an `NSDictionary` can't have multiple keys of the same name, so you'll probably want to create a custom object to hold your data. You could then create a method on that custom object that adds each one of the properties of that object (strings, arrays, numbers etc) to the POST string. – Rob Keniger May 06 '10 at 23:27
  • Excellent thank you very much for that! One last thing if you can help do you know where I can find out more about the format your putting the post string in? I always like to know the full story :) – Tristan May 07 '10 at 00:36
  • Have a look at http://en.wikipedia.org/wiki/MIME#Multipart_messages and http://www.w3.org/TR/html401/interact/forms.html#h-17.13.4.2 – Rob Keniger May 07 '10 at 00:52