Joe Groff
@robtimp @jesse_squires Unowned is faster and allows for immutability and nonoptionality. If you don't need weak, don't use it.
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@jckarter sorry to reply to an old tweet, but could you explain why unowned is faster? Is this documented?
Chris Eidhof
@chriseidhof unowned uses a second refcount in the object. weak refs are tracked in a global table.
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@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. - View other replies
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@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. - View other replies
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@jckarter wait, so as long as there's an unowned ref, memory isn't freed? How does unowned prevent ref cycles then? -
@jckarter when A refers B strongly, and B refers A unowned, it still creates a cycle? Because A only is released after unowned releases? - View other replies
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@chriseidhof The object is destroyed and gives up all its resources when the last strong reference is released. - View other replies
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@chriseidhof The memory for the instance is still allocated but left in a zombie state. - View other replies
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