animation.kt

    private fun fadeIn(view: View) {
        view.apply {
            alpha = 0f
            visibility = View.VISIBLE
            animate()
                .alpha(1f)
                .setDuration(300)
                .setListener(null)
        }
    }

    private fun fadeOut(view: View) {
        view.animate()
            .alpha(0f)
            .setDuration(300)
            .setListener(object : AnimatorListenerAdapter() {
                override fun onAnimationEnd(animation: Animator) {
                    view.visibility = View.INVISIBLE
                }
            })
    }