Question

NSDate conforms to NSCopying protocol. According to the documentation for NSCopying protocol:

a copy must be a functionally independent object with values identical
to the original at the time the copy was made.

But, when I do this:

NSDate *date1 = [NSDate date];
NSDate *date2 = [date1 copy];
NSLog(@"result: date1 0x%x  date2 0x%x", (int)date1, (int)date2);
// "result: date1 0x2facb0  date2 0x2facb0"

The two objects are identical (same object id). What am I missing? How do I get an independent object as a copy?

Answer 1

copy does not guarantee different object pointer. “Functionally independent” means that changes to the original object will not be reflected in the copy, and thus for immutable objects copy may work as retain (I don’t know if this is guaranteed though, probably not).

Try date2 = [[NSDate alloc] initWithTimeInterval:0 sinceDate:date1].