iPhone アプリケーションからサーバーにデータを送信していますが、post String を読み取ると、アプリケーションでクラッシュし、先に進みません
-(void)submitSurveyAnswers{
NSString*survey_question_response_id="1";
NSString*survey_id=@"1";
NSString *question_id =@"1";
NSString *survey_response_answer_id =@"1";
NSString *post =[[NSString alloc] initWithFormat:@"survey_question_response_id=%@&survey_id=%@&question_id=%@&survey_response_answer_id=%@",survey_question_response_id,survey_id,question_id,survey_response_answer_id];
NSLog(post);
NSURL *url=[NSURL URLWithString:@"http://myserver-solutions.com/app/surveyAnswer.php?"];
NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init] ;
[request setURL:url];
[request setHTTPMethod:@"POST"];
[request setValue:postLength forHTTPHeaderField:@"Content-Length"];
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
[request setHTTPBody:postData];
NSError *error;
NSURLResponse *response;
NSData *urlData=[NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
NSString *data=[[NSString alloc]initWithData:urlData encoding:NSUTF8StringEncoding];
NSLog(@"%@",data);
}