how to post the user email password in to json using NSURL I have this information like i have authenticationtoken

How to post user email id & password in to JSON format i have given this information but i am getting error.

How to do this post method i want is if email & password is correct user have to enter to the next screen:

- (IBAction)enterButtonAction:(id)sender {
        NSString *post =[NSString stringWithFormat:@"user[email]=%@&user[password]=%@",[userNameTF text],[passWordTF text],nil];

        NSLog(@"PostData: %@",post);

        NSURL *url=[NSURL URLWithString:@"http:http://ift.tt/17TDEbq"];
        NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
        NSString *postLength = [NSString stringWithFormat:@"%lu", (unsigned long)[postData length]];
        NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init] ;
        [request setURL:url];
        [request setHTTPMethod:@"POST"];
        [request setValue:postLength forHTTPHeaderField:@"Content-Length"];
        [request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
        [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
        [request setValue:@"vz_Bim-_QYyzgJBmv68R" forHTTPHeaderField:@"authentication_token"];

        [request setHTTPBody:postData];

        NSURLResponse *requestResponse;
        NSData *requestHandler = [NSURLConnection sendSynchronousRequest:request returningResponse:&requestResponse error:nil];

        id dict = [NSJSONSerialization JSONObjectWithData:requestHandler options:0 error:nil];

        NSString *id1 = [dict valueForKey:@"id"];
        NSLog(@"id: %@", id1);

        NSString *email = [dict valueForKey:@"email"];
        NSLog(@"email: %@", email);

        NSString *role = [dict valueForKey:@"role"];
        NSLog(@"role: %@", role);

        NSString *phone= [dict valueForKey:@"phone"];
        NSLog(@"phone: %@", phone);

        NSString *full_name = [dict valueForKey:@"full_name"];
        NSLog(@"full_name: %@", full_name);

        NSString *gender = [dict valueForKey:@"gender"];
        NSLog(@"gender: %@", gender);

        if (!requestResponse) {
            NSLog(@"No Request");
        } else {
            NSLog(@"Success");
        }
    }