Android MVP

MVPGreeting.kt

interface View {
    fun setGreeting(greeting: String)
}

interface Presenter {
    fun onDestroy()
    fun getGreeting()
}

class Person(var firstName: String, var lastName: String)

class GreetingPresenter(var view: View?, var model: Person) : Presenter {
    override fun onDestroy() {
        view = null
    }

    override fun getGreeting() {
        view?.let{ v ->
            v.setGreeting("Hello ${model.firstName} ${model.lastName}")
        }
    }
}

class GreetingComponents(view: View) {
    var person: Person = Person("Adrian", "Catalan")
    var presenter: GreetingPresenter = GreetingPresenter(view, person)
}

class GreetingActivity : AppCompatActivity(), View {
    private var components: GreetingComponents = GreetingComponents(this)
    private var presenter: Presenter = components.presenter

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_greeting)

        btnShowGreet.setOnClickListener {
            presenter.getGreeting()
        }
    }

    override fun onDestroy() {
        presenter.onDestroy()
        super.onDestroy()
    }

    override fun setGreeting(greeting: String) {
        txtGreet.text = greeting
    }

}