iPhone App crashing - viewDidLoad - iphone

Question

My iphone app crashes when I add a method to the viewDidLoad in my main viewcontroller:
#import "dbQuestionGetterViewController.h"
#import "dbConnector.h";
#implementation dbQuestionGetterViewController
#synthesize questions;
-(void)viewDidLoad{
//code to initialise view
NSDictionary* arr = [dbConnector getQuestions:2 from:#"http://dev.speechlink.co.uk/David/get_questions.php"];
questions = arr;
[arr release];
[super viewDidLoad];
}
I'm calling a static method from the dbConnector class, but it crashes before even loading..
The method in dbConnector:
//method to
+(NSDictionary*)getQuestions:(NSInteger)sectionId from: (NSString*) url{
//connect to database given by url
//NSError *error = nil;
//NSURLResponse *response = nil;
NSMutableString* myRequestString = [[NSMutableString string]initWithFormat:#"section=%#", sectionId];
NSData *myRequestData = [NSData dataWithBytes: [myRequestString UTF8String] length: [myRequestString length]];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL: [NSURL URLWithString: url]];
[request setValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"content-type"];
[request setHTTPMethod: #"POST"];
//post section
[request setHTTPBody: myRequestData];
//store them in the dictionary
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:url]];
NSString *json = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSDictionary *questions = [json objectFromJSONString];
[json release];
[request release];
return [questions autorelease];
}
what am i doing wrong?

Answer 1

First of all, you're not doing anything with this code:
NSMutableString* myRequestString = [[NSMutableString string]initWithFormat:#"section=%#", sectionId];
NSData *myRequestData = [NSData dataWithBytes: [myRequestString UTF8String] length: [myRequestString length]];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL: [NSURL URLWithString: url]];
[request setValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"content-type"];
[request setHTTPMethod: #"POST"];
//post section
[request setHTTPBody: myRequestData];
Remove it.
Secondly, questions is already autoreleased.
NSDictionary *questions = [json objectFromJSONString]; // < autoreleased
So simply doing return questions; should work.
This also means that you should not under any case release this returned value. Thus, get rid of this:
[arr release];

Answer 2

The NSDictionary that is returned from the static method is autoreleased. But you release it in the viewDidLoad method.

Answer 3

You are releasing the arr object that getQuestions returns. Since you've already marked this object as autorelease you don't need to explicitly release it yourself. Remove the following line from viewDidLoad and you should be set:
[arr release];
Also, your myRequestString is suspect. You are calling the string class method, which returns a fully allocated and initialized string, but then you're calling initWithFormat on it, which is normally for strings you've just alloc-ed. Replace that line with:
[[NSMutableString alloc]initWithFormat:#"section=%#", sectionId]
and then release it right after your [request release].