Question

Here is the code:

- (id)copyWithZone:(NSZone*)zone {
    ExecutedOrderInfo* copy = [[self class] allocWithZone:zone];
    copy.executedPrice = self.executedPrice;
    copy.executedQuantity = self.executedQuantity;
    return (id)copy;
}

The question is, is it necessary to release “copy” in above code? Or release it when someone called it?

Answer 1

No, not in this method. Methods that start with copy must return non-autorleased objects with retain count 1. Just as you do.

PS: the cast in return (id)copy is not needed. id is the abstract object type and much more general than your concrete class. Casts are only needed when having a concrete class that should be treated as a different one — like a subclass after doing a subclass check.

PPS: Your method lacks an init. It’s not good to just alloc a instance. Instead do something like this: [[[self class] allocWithZone:zone] init];