Question

I did a build and analyze and was warned about a potential leak of an object stored into ‘locationManager’. I was wondering how this should be handled properly. Here’s the code:

// Compass Code

    CLLocationManager *locationManager = [[CLLocationManager alloc] init];
    locationManager.delegate = self;
    if ([CLLocationManager locationServicesEnabled] && 
        [CLLocationManager headingAvailable]) {
        [locationManager startUpdatingLocation];
        [locationManager startUpdatingHeading];
        locationManager.headingFilter = 2; // 2 degrees

    } else {

    NSLog(@"Can't report heading");

    }

thanks for any help

Answer 1

On the first line you alloc the location manager. This means you own that reference, and you should release it when you are done.

You need to either release the location manager when you have finished setting it up:

// ...
locationManager.headingFilter = 2; // 2 degrees
[locationManager release];

Or autorelease it on the same line you alloc it:

CLLocationManager *locationManager = [[[CLLocationManager alloc] init] autorelease];

Having said that, you should probably be storing the location manager in an instance variable so you can stop the location updates at some point. Otherwise self might get deallocated and the location manager will continue sending messages to that deallocated object. This will cause a crash.

After making an instance variable, your dealloc should probably have this:

- (void)dealloc
{
    // ...
    locationManager.delegate = nil;
    [locationManager stopUpdatingLocation];
    [locationManager release];
    // ...
    [super dealloc];
}

Clearing the delegate will make sure the location manager will not send any messages to us once we have been deallocated. Then we stop the location updates and release the instance variable because we no longer need it.