Swift version: 5.4
Unowned variables are similar to weak variables in that they provide a way to reference data without having ownership. However, weak variables can become
nil – they are effectively optional. In comparison, unowned variables must never be set to nil once they have been initialized, which means you don't need to worry about unwrapping optionals.
The most common place you'll see unowned variables is with closures that declare
[unowned self] – this means "I want to reference
self inside this closure but I don't want to own it." Why
unowned rather than
weak? Both would work, but let's face it: if
self is nil inside a closure, something has gone wrong!
SPONSORED From August 2nd to 8th you can join a FREE crash course for mid/senior iOS devs who want to achieve an expert level of technical and practical skills – it’s the fast track to being a complete senior developer!
Available from iOS 7.0
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
Link copied to your pasteboard.