Force unwrapping after optional chaining

[krilnon (Kyle Murray)]

I think Joe’s answer here should help:

Confirming order of operations

This isn't guaranteed. Releases may be optimized to happen earlier than this, to any point after the last formal use of the strong reference. Since the strong reference loaded in order to evaluate the left-hand side weakProperty?.variable is not used afterward, there is nothing keeping it alive, so it could be immediately released. If there are any side effects in the getter for variable that cause the object referenced by weakProperty to be deallocated, nil-ing out the weak reference, then that…