Memory leak on instrument at NSString stringWithFormat

Question

In my appDelegate I am using LocationManager :

- (void)locationManager: (CLLocationManager *)manager
    didUpdateToLocation: (CLLocation *)newLocation
           fromLocation:(CLLocation *)oldLocation
{

    float latitude = newLocation.coordinate.latitude;
     strLatitude = [NSString stringWithFormat:@"%f",latitude];
    float longitude = newLocation.coordinate.longitude;
    strLongitude = [NSString stringWithFormat:@"%f", longitude];
    [self CheckOperation];

}  

strLatitude and strLongitude are global strings. This is absolutely fine. Even on analyzing the application I don't get any memory leak. But when I profile my application I receive a memory leak at

strLatitude = [NSString stringWithFormat:@"%f",latitude];  

and

strLongitude = [NSString stringWithFormat:@"%f", longitude];

of 32 bytes .

How can I fix that?

Answer 1

Are you sure you're seeing a leak and not simply just an allocation?

If you do actually have a leak here then there are some potential suspects:

Are you using ARC? If not, here are some possible problems:

• Are you releasing it in dealloc?

• If this method gets run more than once, you aren't releasing the last value before you reassign it.

• If you're not using copy semantics, and you're passing this string reference off to someone else, and they aren't properly releasing it, you'll also get a backtrack to this line.

EDIT:

(Per the comments below)

You should realize that stringWithFormat: is allocating a string and queuing up an autorelease on it... so you need to retain it somewhere.

I assumed you were doing this somewhere because you aren't getting an "EXC_BAD_ACCESS" - but rather, supposedly, a leak.

You shouldn't be leaking an autoreleased object unless you've retained it somewhere (hence the assumption).

Given you need to be retaining it somewhere, my above suggestions are valid - each retain needs a matching release.

I do agree that you should be using properties for these strings.

It's simple to convert them - and takes care of a lot of things for you.

In your Interface:

@property (nonatomic, copy) NSString * strLatitude; 

In your Implementation:

@synthesize strLatitude;

To assign:

self.strLatitude = ...

(the "self." part is important)

And make sure you set that to nil in dealloc.