Proper JSON encoding for HTTP POST request in iOS - ios

Question

Posted a query previously about JSON parsing not working properly. Did more looking into it with a packet sniffer and also with another client that works properly and found out it's a syntax thing, that I still can't seem to solve.
The code in the bottom makes the HTTP request to have the JSON in it as:
{"key":"value"}
And my server is actually looking for a JSON in the following syntax:
key=%22value%22
I tried to write some code that does this manually, but figured there must be something out of the box for iOS, and I don't want to have faults in the future.
I messed around with it for a while trying to find the right code for the job, but couldn't (you can see some code I tried commented out). Can anyone help me?
+ (NSString*)makePostCall:(NSString*)urlSuffix
keys:(NSArray*)keys
objects:(NSArray*)objects{
NSDictionary *params = [NSDictionary dictionaryWithObjects:objects forKeys:keys];
// NSString *dataString = [self getDataStringFromDictionary:params];
// NSData *jsonData = [dataString dataUsingEncoding:NSUTF8StringEncoding];
NSError *error;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:params
options:0
error:&error];
// id jsonObject = [NSJSONSerialization JSONObjectWithData:jsonData options:kNilOptions error:&error];
// NSLog(#"%#", jsonObject);
if (!jsonData) {
// should not happen
NSError *error;
NSLog(#"Got an error parsing the parameters: %#", error);
return nil;
} else {
// NSString *jsonRequest = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
// NSLog(#"%#", jsonRequest);
NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:#"%#%#", urlPrefix, urlSuffix]];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url
cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:20.0];
// NSData *requestData = [jsonRequest dataUsingEncoding:NSUTF8StringEncoding];
[request setHTTPMethod:#"POST"];
[request setValue:#"application/json" forHTTPHeaderField:#"Accept"];
// [request setValue:#"application/x-www-form-urlencoded;charset=UTF-8" forHTTPHeaderField:#"Content-Type"];
[request setValue:#"application/json; charset=utf-8" forHTTPHeaderField:#"Content-Type"];
[request setHTTPBody: jsonData];
NSURLResponse * response = nil;
NSError * error = nil;
NSData * data = [NSURLConnection sendSynchronousRequest:request
returningResponse:&response
error:&error];
// TODO: handle error somehow
NSString *returnString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
return returnString;
}
}