Deinit experiement

deinit-experiment.swift

class Ref {
  weak var obj: Obj? {
    didSet { print("didSet", obj as Any) }
  }
}

class Obj {
  weak var ref: Ref?

  func unlink(from ref: Ref) {
    print(ref.obj as Any)
  }

  deinit {
    print("deinit")
    ref.map(unlink(from:))
  }
}

var obj: Obj? = Obj()
let ref = Ref()
ref.obj = obj
print(obj?.ref as Any)
obj = nil

/*
 * Conclusion:
 * If an object calls `deinit` it means that if it's instance
 * contains a reference to an other object that previously
 * referred to the current instance, it will be `nil`.
 */