objective c - Swift setting object to nil does not release memory -

i have optional property of class of type viewcontroller

var vc : uiviewcontroller()?

i later nowadays view controller popover using custom code.

upon dismissing popover controller set variable nil

vc = nil

but object never release (and dealloc method of viewcontroller not called)

this worked in objective c not in swift me

is there else have in order forcefulness object released in swift (other setting nil)?

objective-c swift memory-management

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