I need to deep copy a custom object that has objects of its own. I've been reading around and am a bit confused as to how to inherit NSCopying and how to use NSCopyObject.
As always with reference types, there are two notions of "copy". I'm sure you know them, but for completeness.
You want the latter. If this is one of your own objects, you need simply adopt the protocol NSCopying and implement -(id)copyWithZone:(NSZone *)zone. You're free to do whatever you want; though the idea is you make a real copy of yourself and return it. You call copyWithZone on all your fields, to make a deep copy. A simple example is
@interface YourClass : NSObject <NSCopying>
{
SomeOtherObject *obj;
}
// In the implementation
-(id)copyWithZone:(NSZone *)zone
{
// We'll ignore the zone for now
YourClass *another = [[YourClass alloc] init];
another.obj = [obj copyWithZone: zone];
return another;
}