How do I test the equality of two CLLocations

Question

I'm having a problem with isEqual:

The code:

 if (currentAnchor isEqual:currentBusiness.getCllLocation))
    {
        do a;
    }
    else
    {
        do b;
    }

currentanchor and currentbusiness.getCllocation are locations

But if they are the same, why is function b called? Is something wrong with my code?

Answer 1

I assume both of these objects are of type CLLocation, based on the name of getClLocation.

CLLocation doesn't have any specification on what its isEqual: method does, so it's likely just inheriting the implementation of NSObject, which simply compares the pointers of the objects. If you've got two distinct objects with identical data, that isEqual: implementation would return NO. And if you've got two distinct objects with just a slight variation in location, they definitely would not be equal.

You probably don't want isEqual: when comparing location objects. Rather, you probably want to use the distanceFromLocation: method on CLLocation. Something like this would be better:

CLLocationDistance distanceThreshold = 2.0; // in meters
if ([currentAnchor distanceFromLocation:currentBusiness.getCllLocation] < distanceThreshold)
{
  do a;
}
else
{
  do b;
}

Answer 2

It's been a while.

What I did is similar with BJ Homer. I just add this.

@interface CLLocation  (equal)
- (BOOL)isEqual:(CLLocation *)other;
@end

@implementation CLLocation  (equal)

- (BOOL)isEqual:(CLLocation *)other {


    if ([self distanceFromLocation:other] ==0)
    {
        return true;
    }
    return false;
}
@end

I was surprised I were the one asking this question :)