Cocoa error 3840 using JSON (iOS)

Question

I'm trying to send data to a server and receive the response in JSON format. The problem is that the server has to return "success" or "fail" but it returns "(null)".

Here's the returned error:

Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn’t be completed. (Cocoa error 3840.)" (JSON text did not start with array or object and option to allow fragments not set.) UserInfo=XXXXXXXXX {NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.}

Is it possible that the error is in the server script?

Here's my function to send the data and receive the response:

- (void) putData:(NSString *)parameter valor:(NSString *)valor {

    NSString *rawString = [NSString stringWithFormat:@"%@=%@", parameter, valor];
    NSData *data = [rawString dataUsingEncoding:NSUTF8StringEncoding];
    NSURL *url = [NSURL URLWithString:@"http://www.xxx.xxx/xxx.php"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    [request setHTTPMethod:@"PUT"];
    [request setHTTPBody:data];
    NSURLResponse *response;
    NSError *error;
    NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
    NSMutableDictionary *json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];
    NSLog(@"responseData: %@ error: %@", json, error);
}

Stu Stu · Accepted Answer · 2013-01-05T11:32:25

Unless you pass the option NSJSONReadingAllowFragments to [NSJSONSerialization JSONObjectWithData:options:error:] the response from the server must be valid JSON with a top level container which is an array or dictionary.

for example:

    { "response" : "Success" }

P.S. If you want a mutable dictionary you must also include NSJSONReadingMutableContainers in your options.

Cocoa error 3840 using JSON (iOS)

3 Answers