How can I make a deep copy in Objective-C?

Question

I\'m learning ios development and I\'m confused with deep copying in Objective-C. For example,I have three class below. Now I want to deep copy ClassA, can anybody teach me

Answer 1

Following the explanation at http://www.techotopia.com/index.php/Copying_Objects_in_Objective-C

"This can be achieved by writing the object and its constituent elements to an archive and then reading back into the new object."

@implementation ClassA

- (id)copyWithZone:(NSZone*)zone{
    NSData *buffer;
    buffer = [NSKeyedArchiver archivedDataWithRootObject:self];
    ClassA *copy = [NSKeyedUnarchiver unarchiveObjectWithData: buffer];
    return copy;
}
@end