is it allowed to call [obj copy] in ObjC with ARC?

Question

There's one thing I don't understand regarding ARC: how should we now treat local variables that were created using [... copy]? If I make a property with (copy) flag, ARC will handle this automatically, but as far as I know there's no __copy flag for variables.

I've tested this with such code:

@interface Foo : NSString
@end

@implementation Foo

- (void) dealloc {
  NSLog(@"%p deallocated", self);
}

- (NSUInteger) length {
  return 1;
}

- (unichar) characterAtIndex: (NSUInteger) i {
  return 'x';
}

@end

- (void) foo {
  Foo *f = [[Foo alloc] init];
  NSLog(@"%p", f);

  Foo *f2 = [f copy];
  NSLog(@"%p", f2);
}

What I get is:

0x102406530
0x102015f10
0x102406530 deallocated

I never get "0x102015f10 deallocated", which would suggest the copied variable doesn't get released. It doesn't even get autoreleased, because when I made another method [Foo foo] that returned an autoreleased object, I did get a "deallocated" message a moment later.

So is there any way I can cause it to be released without converting it to a property?

Answer 1

Ok, my bad - ARC does actually handle copied objects properly. I got wrong results because of using NSString for the test, because I wanted to use a class that already implemented copying instead of implementing it explicitly; when I repeated the test on a class inheriting from NSObject and implementing copyWithZone: by returning [[Foo alloc] init], I got two "deallocated" messages. Thanks to @Paul.s for pointing that out.