fragmentcallback-2

YourActivity.kt

override fun onCreate(savedInstanceState: Bundle?) {
    showFragment()
}

// callback listener
private val fragmentBackPressedListener = object : OnFragmentCallback {
    override fun onFragmentBackPressed() {
        foo()
    }
}

// launch fragment
private val showFragment() {
  val frag = YourCustomFragment(
      backPressedListener = backPressedListener
  )
  frag.show(parentFragmentManager, "PopupFragment")
}