Part of me wants to see this interface as:  

```+ (NSString*)formatLatitudeWithCoordinate:(CLLocationCoordinate2D) coord;```
```+ (NSString*)formatLongitudeWithCoordinate:(CLLocationCoordinate2D) coord;```

At least then it's a bit more readable and we get type checking. You can do whatever you like in the helper Utility class to make this happen.