[jarpadat]

In general, a retained object is deallocated on last release. However ownership of some objects somewhere may have been given to an autoreleasepool, in which case “the last release” for those objects will come from the pool. To what extent this happens is implementation-defined.

Swift and ObjC implementations have levers which discourage objects being sent to the pool in common cases. It is possible to pull them from other languages but not easy.