didSet behaviour

print("--- Example 1 ---")
protocol MyProtocol {
    var property: AnyObject? { get set }
}

protocol MyClassProtocol: class {
    var property: AnyObject? { get set }
}

class MyViewController: UIViewController {
    var viewModel: ClassA! {
//    var viewModel: MyProtocol! {
//    var viewModel: MyClassProtocol! {
        didSet {
            print("didSet viewModel")
        }
    }
}

class ClassA: MyProtocol, MyClassProtocol {
    var property: AnyObject? {
        didSet {
            print("didSet property in ClassA")
        }
    }
}

class ClassB {}

let vc = MyViewController()
vc.viewModel = ClassA()
vc.viewModel.property = ClassB()




print("\n--- Example 2 ---")
class SecondViewController: UIViewController {
    var valueTypeProperty: StructA! {
        didSet {
            print("didSet valueTypeProperty")
        }
    }
}

struct StructA {
    var property: Int? {
        didSet {
            print("didSet property in StructA")
        }
    }

    var referenceProperty: ClassB? {
        didSet {
            print("didSet reference property in StructA")
        }
    }
}

let secondVC = SecondViewController()
secondVC.valueTypeProperty = StructA()
secondVC.valueTypeProperty.property = 42
secondVC.valueTypeProperty.referenceProperty = ClassB()