Open Radar

 
Summary:
UIBezierPath conforms to NSCopying, but its -copyWithZone: always returns an instance of UIBezierPath. This means that subclasses cannot easily implement copyWithZone: because [super copyWithZone:] returns an object of the wrong class.

Steps to Reproduce:

- Use the following subclass:

	@interface MyPath : UIBezierPath
	@end
	@implementation MyPath
	- (id)copyWithZone:(NSZone *)zone
	{
		MyPath *obj = [super copyWithZone:zone];
		// obj is of the wrong class; can't set custom properties!
		return obj;
	}
	@end

- Test with the following code:

	MyPath *path = [[MyPath alloc] init];
	NSLog(@"Path: %@", [path class]);
	NSLog(@"Copy: %@", [[path copy] class]);

Expected Results:
[path class] == [[path copy] class] == [MyPath class]

Actual Results:
[path class] == [MyPath class], but [[path copy] class] == [UIBezierPath class]

Notes:
According to the NSCopying documentation:
"If a subclass inherits NSCopying from its superclass and declares additional instance variables, the subclass has to override copyWithZone: to properly handle its own instance variables, invoking the superclass’s implementation first."