How to write data to the web server from iPhone application?
I am looking forward for posting some data and information on the web server through my iPhone application. I am not getting the way to post data to the web server from iPhone sdk.
Answer
It depends in what way you want to send data to the web server. If you want to just use the HTTP POST method, there are (at least) two options. You can use a synchronous or an asynchronous NSURLRequest. If you only want to post data and do not need to wait for a response from the server, I strongly recommend the asynchronous one, because it does not block the user interface. I.e. it runs "in the background" and the user can go on using (that is interacting with) your app. Asynchronous requests use delegation to tell the app that a request was sent, cancelled, completed, etc. You can also get the response via delegate methods if needed.
Here is an example for an asynchronous HTTP POST request:
// define your form fields here:
NSString *content = @"field1=42&field2=Hello";
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:@"http://www.example.com/form.php"]];
[urlRequest setHTTPMethod:@"POST"];
[urlRequest setHTTPBody:[content dataUsingEncoding:NSISOLatin1StringEncoding]];
// generates an autoreleased NSURLConnection
[NSURLConnection connectionWithRequest:request delegate:self];
Please refer to the NSURLConnection Class Reference for details on the delegate methods.
You can also send a synchronous request after generating the request:
[NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
If you pass a NSURLResponse ** as returning response, you will find the server's response in the object that pointer points to. Keep in mind that the UI will block while the synchronous request is processed.