MainActivity.kt

// Instantiate Paging Adapter
mAdapter = object : FirestorePagingAdapter<Post, PostViewHolder>(options) {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): PostViewHolder {
        val view = layoutInflater.inflate(R.layout.item_post, parent, false)
        return PostViewHolder(view)
    }

    override fun onBindViewHolder(viewHolder: PostViewHolder, position: Int, post: Post) {
        // Bind to ViewHolder
        viewHolder.bind(post)
    }

    override fun onError(e: Exception) {
        super.onError(e)
        Log.e("MainActivity", e.message)
    }

    override fun onLoadingStateChanged(state: LoadingState) {
        when (state) {
            LoadingState.LOADING_INITIAL -> {
                swipeRefreshLayout.isRefreshing = true
            }

            LoadingState.LOADING_MORE -> {
                swipeRefreshLayout.isRefreshing = true
            }

            LoadingState.LOADED -> {
                swipeRefreshLayout.isRefreshing = false
            }

            LoadingState.ERROR -> {
                Toast.makeText(
                    applicationContext,
                    "Error Occurred!",
                    Toast.LENGTH_SHORT
                ).show()
                swipeRefreshLayout.isRefreshing = false
            }

            LoadingState.FINISHED -> {
                swipeRefreshLayout.isRefreshing = false
            }
        }
    }
}