i need to use a CLLocation - iphone

Question

I need to read my position from GPS!
The problem is that i need to do out from the method
- (void)locationUpdate:(CLLocation *)location;
So... this is how i'm working:
in the .h file i have this
CLLocation *mylocation;
in the -viewDidLoad
mylocation = [[CLLocation alloc] init];
locationController = [[CLController alloc] init];
locationController.delegate = self;
[locationController.locationManager startUpdatingLocation];
then
- (void)locationUpdate:(CLLocation *)location {
mylocation = location;
}
and it works, if i use NSLog (on mylocation) i see my real location!
But... in another method (an IBAction connected with a UIButton) i want to use "mylocation"!
It's not working and i don't know why!
If, in this method, i try to do this
NSLog(#"%#", mylocation);
the console report this:
<+0.00000000, +0.00000000> +/- 0.00m (speed -1.00 mps / course -1.00) # 3/10/11 7:21:24 PM Central European Time
So the variable is empty!
Why??
PS= also in my IBAction i have, of course, this
mylocation = [[LCLocation alloc] init];
otherwise the app crashes!

Answer 1

This line:
mylocation = location;
Is setting mylocation's memory pointer to the one returned by the location manager, which later is getting released.
EDITED:
mylocation = [[CLLocation alloc] initWithLatitude:location.coordinate.latitude longitude:location.coordinate.longitude];

Answer 2

also in my IBAction i have, of course, this
mylocation = [[LCLocation alloc] init];
So you get zero values because you always overwrite your location value with newly created blank location - you should not do that.
The problem that makes your application crash is that in locationUpdate method you get autoreleased value, so in order to ensure that its valid outside of that method you must retain it. (and not forget to release old value). The easiest way to do that is create a property for myLocation ivar and access ivar using it:
// .h file
#property (nonatomic, retain) CLLocation *myLocation;
// .m
#synthesize myLocation;
...
- (void)locationUpdate:(CLLocation *)location {
self.mylocation = location;
}
- (void) dealloc{
[myLocation release];
myLocation = nil;
...
[super dealloc];
}