CLLocation memory issues

Question

I've some memory issues with CLLocation.

CLLocation *annotation = [[CLLocation alloc] initWithLatitude:[[tempDict objectForKey:@"lat"] doubleValue] longitude:[[tempDict objectForKey:@"lon"]doubleValue]];
CLLocation *item2 = [[CLLocation alloc] initWithLatitude:[newLatString doubleValue] longitude:[newLongString doubleValue]];
cell.detailTextLabel.text = [NSString stringWithFormat:@"%.1f km",[item2 distanceFromLocation:annotation]/1000];
[annotation release];
[item2 release];

So I tried to do this, but I realised that you can't set the annotation's coordinate.

CLLocationCoordinate2D tempCoordinate = annotation.coordinate;
tempCoordinate.latitude = [[tempDict objectForKey:@"lat"] doubleValue];
tempCoordinate.longitude = [[tempDict objectForKey:@"lon"] doubleValue];
    annotation.coordinate = tempCoordinate;

Is there a workaround this? I don't want to be alloc/initing a CLLocation everytime cellForRowAtIndexPath is called..

Answer 1

your resultant object is an NSString - just create a class which contains an NSString, as well as references/ivars of the intermediate data where necessary. then using an observer idiom, just update the cells when the string changes (design it so the string depends on the coordinates). you could probably make a class which takes a set of arguments at initialization (e.g. coordinates), creates an NSString during initialization, and then refer to the result if your data never changes. it really depends on what data you expect will mutate, and at what frequency.

Answer 2

I don't want to be alloc/initing a CLLocation everytime cellForRowAtIndexPath is called..

Why not? Do you know it's causing performance problems? You're releasing them right away, so they aren't taking up extra memory. CLLocation looks like a pretty lightweight class, and the Objective-C runtime is heavily optimized, so they probably alloc / init pretty quickly. Until you see scrolling / perf / memory issue, I would go with what works and is easy to maintain.

Premature optimization is the root of all evil - Donald Knuth