FranDepascuali

extension ViewModelBindable where Self: AnyObject {

    public var viewModel: ViewModel? {
        // store view model
    }

}

FranDepascuali

public protocol ViewModelBindable: class {

    typealias ViewModel

    var viewModel: ViewModel? { get set }

    func bindViewModel(viewModel: ViewModel)

    func unbindViewModel(viewModel: ViewModel)

FranDepascuali

public class MyViewController: UIViewController {
    var viewModel: MyViewModel? {
        willSet(maybeViewModel) {
            if let _ = self.viewModel {
                unbindViewModel()
            }
        }
        
        didSet {
            if isViewLoaded(), let viewModel = self.viewModel {