Difference between Category and Class Extension?

Question

What is the difference between a Category and a Class Extension. I believe both are used to add custom methods in existing classes. Can someone throw light on this? Examplif

Answer 1

@interface SomeClass ()


- (void) anAdditionalMethod;


@end

I think it is not the way to declare Category. Category must have a name

@interface SomeClass (XYZ)


- (void) anAdditionalMethod;


@end

for example

@interface NSMutableArray (NSMutableArrayCreation)

+ (id)arrayWithCapacity:(NSUInteger)numItems;
- (id)initWithCapacity:(NSUInteger)numItems;

@end

Declared for NSMutableArray by Apple