objective c - Managing the memory for an object passed in to an in-out argument -

i wonder how memory management must done method parameters used pass values method , (optionally) return updated values method.

for example, -validate<key>:error: method in kvc has (id *)iovalue parameter can updated method. can return autoreleased object should input object when updating? there conventions case?

there isn't particularly complex replacing object reference new object, taking nil reference , making valid when object first created.

if using arc compiler realise old reference has been replaced, in other situation. if using mrr required observe normal retain/release conventions in order avoid memory leak.