Post JSON to a webservice

Make sure you have JSON Framework installed first.

This is a continuation of UIImageView in a custom cell

Here is a simple little code snippet on how to post some JSON to a webservice.

NSString *requestString = [NSString stringWithFormat:@"json=%@", [loginDict JSONFragment], nil];
NSData *requestData = [NSData dataWithBytes: [requestString UTF8String] length: [requestString length]];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL: [NSURL URLWithString: @"http://domain.com/api/login/"]];
[request setHTTPMethod: @"POST"];
[request setHTTPBody: requestData];

NSData *returnData = [ NSURLConnection sendSynchronousRequest: request returningResponse: nil error: nil ];
NSString *returnString = [[NSString alloc] initWithData:returnData encoding: NSUTF8StringEncoding];

// decoding the json
NSDictionary *loginArray = [NSDictionary alloc];
loginArray = [returnString JSONValue];

So below is what each line does.

  • First we format the request string. What I am doing there is taking a whole dictionary and making it a JSON object. I then assign that to the json variable to post in. So in PHP land that would come in as $_POST['json']  and I could do like json_decode($_POST['json']) and turn it into an array I can work with in PHP
  • The next line turns the request into a data object so we know how big the string is.
  • Now we setup the URL to post the request to
  • We are setting the method to a post in html land it is like <form method=”POST”>
  • Now are are setting up the body of the post with our data
  • We now make the connection to the server and then get a data string back
  • We decode the data stream into a NSString object
  • Since you send in JSON I expect you get JSON back so we take the contents of the NSString and turn it into a NSDictionary

Pretty simple. That is all there is to it.

August 28, 2008 · Filed Under Uncategorized

Comments

7 Responses to “Post JSON to a webservice”

  1. Amit on September 8th, 2008 3:47 pm

    can you some example of how to connect to .NET web-services using SOAP?

  2. mikezupan on September 8th, 2008 7:19 pm

    @Amit

    The quick answer to that is no.

    1) I am not a MS person. I haven’t touched windows in ages cept for my laptop I keep for my future wife to use
    2) I have always hated SOAP with a passion.

    Sorry!

  3. Using threads for a JSON request : Iphone Noob on September 26th, 2008 8:08 am

    [...] This is a continuation of Post JSON to a webservice [...]

  4. chris on February 7th, 2009 10:03 am

    Great tutorial!

    There is one small change I had to do. The [loginDict JSONFragment] isn’t url encoded, which causes problems if any of the values in the dictionary contains an ampersand (&). Otherwise, no problems!

  5. Stanley on April 10th, 2009 11:05 pm

    Thanks your code, but I try hard to get Json from iphone in PHP. But it didn’t work, could you please have examples about this.

  6. Fernando on September 24th, 2009 2:20 pm

    Any chance you can show how to post a file via JSON?

    Thanks!

  7. Nauman.Khattak on July 26th, 2010 5:57 am

    Hello sir.
    i am developing an iphone application for a youtube like website.

    I want to talk with website database from my iphone application.

    want to insert user comment,rating, and other data to website database. Will you guide me please..
    i am very fresh to iphone development.

Leave a Reply