Joe Groff

@robtimp @jesse_squires Unowned is faster and allows for immutability and nonoptionality. If you don't need weak, don't use it.

@jckarter sorry to reply to an old tweet, but could you explain why unowned is faster? Is this documented?

@chriseidhof unowned uses a second refcount in the object. weak refs are tracked in a global table.

@jckarter thanks, that clarifies it =)

@chriseidhof It's a space/time tradeoff. unowned can't free memory until unowned refs die, but weak frees immediately when strong refs die.

@jckarter ah, so the second refcount tracks how many things refer to that unowned object?

@chriseidhof Yeah, so we can check whether the object is still alive before strong-retaining it again.

@jckarter wait, so as long as there's an unowned ref, memory isn't freed? How does unowned prevent ref cycles then?