iOS7 background fetch EXC_BAD_ACCESS - ios

Question

I'm trying to implement a background fetch method to get new data, but it's giving me an error with an NSMutable Dictionary. Here's my code
In my appDelegate under performFetchWithCompletionHandler I have:
UINavigationController *navigationController = (UINavigationController*) self.window.rootViewController;
id topViewController = navigationController.topViewController;
if ([topViewController isKindOfClass:[viewController class]])
{
[(viewController*)topViewController autologin];
}
else
{
completionHandler(UIBackgroundFetchResultNewData);
}
This calls auto login in my view controller
- (void) autologin
{
NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
NSString* username = [defaults valueForKey:#"username"];
NSString* password = [defaults valueForKey:#"password"];
[self login:username password:password];
}
Which then calls login
- (void)login:(NSString*)username password:(NSString*) password
{
NSDictionary *login = [[NSDictionary alloc] initWithObjectsAndKeys:username, #"username", password, #"password", NO, #"showNotification", nil];
NSOperationQueue* backgroundQueue = [NSOperationQueue new];
ch = [[backgroundProcess alloc] init];
NSInvocationOperation* operation = [[NSInvocationOperation alloc] initWithTarget:ch selector:#selector(runEvents:) object:login];
[backgroundQueue addOperation:operation];
operation = [[NSInvocationOperation alloc] initWithTarget:self selector:#selector(checkStatus) object:nil];
[backgroundQueue addOperation:operation];
}
Everything works if my app is running in the foreground and I call the login function, but with the performFetchWithCompletionHandler as soon as it hits
NSDictionary *login = [[NSDictionary alloc] initWithObjectsAndKeys:username, #"username", password, #"password", NO, #"showNotification", nil];
I get EXC_BAD_ACCESS. Any help would be appreciated!

Answer 1

Not sure why you are only crashing from the background. One error I see is that you can't use "NO" (a scalar BOOLEAN value) in a dictionary directly. NSDictionary objects can only contain objects. You need to convert the NO value to an NSNumber. With recent versions of Objective C you can use the syntax #(NO) to convert a scalar to an NSNumber. This is the equivalent of
[NSNumber numberWithBool: NO];
I doubt if that is the source of your crash, but it is an error in your code.
I don't know the object ownership rules of NSInvocationOperation off the top of my head. Since the introduction of GCD I haven't used NSOperations or NSOperationQueues. You might want to think about using GCD based calls instead.