How to call JSON in ios (post method)

//POST method

    

    NSString *post = [NSString stringWithFormat:@"test=Message&this=isNotReal"];

    NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];

    

    NSString *postLength = [NSString stringWithFormat:@"%lu", (unsigned long)[postData length]];

    

    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];

    [request setURL:[NSURL URLWithString:@"http://api.geonames.org/citiesJSON?north=44.1&south=-9.9&east=-22.4&west=55.2&lang=de&username=demo "]];

    [request setHTTPMethod:@"POST"];

    [request setValue:postLength forHTTPHeaderField:@"Content-Length"];

    [request setHTTPBody:postData];

    

    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];

    [[session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

        

        NSString *requestReply = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];

        NSLog(@"requestReply: %@", requestReply);

        data = [requestReply dataUsingEncoding:NSUTF8StringEncoding];

        NSLog(@"data convert into bits %@" , data);

        

        keyvalue= [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];