Swift 3 - didSet for the opposite direction?

Question

Let's say I have these two classes:

class A {}
class B{
   var myA:A?
}

I want to know when that happens:

let b = B()
let a = A()

b.myA = a    // <<<---- I want to observe this from my A class

I would also like to know who is the owner(In this case, b ).

Sort of like a didSetSelfAsAProperty(ofOwner:AnyObject).

What I am trying to achieve: We have MVVM architecture in our project. I noticed that I need to set both directions when initializing an instance of a view model/view.I need to tell the view model who's its view and vice versa.

Any ideas?

Answer 1

It seems that you're looking for the Observer Pattern. You could achieve it with either callbacks, KVO or third party libraries.