Classes should only hold ``++weak++`` references to delegate fields with ``++class++`` type. Otherwise, the owning class will have a ``++strong++`` reference to its delegate, and vice versa, and the OS won't be able to deallocate either of them..
Note that this only applies to non-computed delegate fields in classes, and not to fields in ``++struct++``s and ``++enum++``s.
Problem of reference cycles is an important one in Swift (see this https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/AutomaticReferenceCounting.html[doc]), but in order to track this pattern we need a semantic information, which we don't have.
