MainActivity.kt

package heatwave.ryanaird.com.swipyrecyclerview

import android.graphics.Canvas
import android.graphics.Color
import android.graphics.drawable.ColorDrawable
import android.graphics.drawable.Drawable
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.support.v4.content.ContextCompat
import android.support.v7.widget.DividerItemDecoration
import android.support.v7.widget.LinearLayoutManager
import android.support.v7.widget.RecyclerView
import android.support.v7.widget.helper.ItemTouchHelper
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    private lateinit var viewAdapter: RecyclerView.Adapter<*>
    private lateinit var viewManager: RecyclerView.LayoutManager
    private lateinit var colorDrawableBackground: ColorDrawable
    private lateinit var deleteIcon: Drawable
    private var dataset = mutableListOf("Chicken", "Fish", "Beef", "Pork", "Lamb")

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

        viewAdapter = MainAdapter(dataset)
        viewManager = LinearLayoutManager(this)

        colorDrawableBackground = ColorDrawable(Color.parseColor("#ff0000"))
        deleteIcon = ContextCompat.getDrawable(this, R.drawable.ic_delete)!!

        recyclerview.apply {
            setHasFixedSize(true)
            adapter = viewAdapter
            layoutManager = viewManager
            addItemDecoration(DividerItemDecoration(this.context, DividerItemDecoration.VERTICAL))
        }

        val itemTouchHelperCallback = object : ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT) {
            override fun onMove(recyclerView: RecyclerView, viewHolder: RecyclerView.ViewHolder, viewHolder2: RecyclerView.ViewHolder): Boolean {
                return false
            }

            override fun onSwiped(viewHolder: RecyclerView.ViewHolder, swipeDirection: Int) {
                (viewAdapter as MainAdapter).removeItem(viewHolder.adapterPosition, viewHolder)
            }

            override fun onChildDraw(
                c: Canvas,
                recyclerView: RecyclerView,
                viewHolder: RecyclerView.ViewHolder,
                dX: Float,
                dY: Float,
                actionState: Int,
                isCurrentlyActive: Boolean
            ) {
                val itemView = viewHolder.itemView
                val iconMarginVertical = (viewHolder.itemView.height - deleteIcon.intrinsicHeight) / 2

                if (dX > 0) {
                    colorDrawableBackground.setBounds(itemView.left, itemView.top, dX.toInt(), itemView.bottom)
                    deleteIcon.setBounds(itemView.left + iconMarginVertical, itemView.top + iconMarginVertical,
                        itemView.left + iconMarginVertical + deleteIcon.intrinsicWidth, itemView.bottom - iconMarginVertical)
                } else {
                    colorDrawableBackground.setBounds(itemView.right + dX.toInt(), itemView.top, itemView.right, itemView.bottom)
                    deleteIcon.setBounds(itemView.right - iconMarginVertical - deleteIcon.intrinsicWidth, itemView.top + iconMarginVertical,
                        itemView.right - iconMarginVertical, itemView.bottom - iconMarginVertical)
                    deleteIcon.level = 0
                }

                colorDrawableBackground.draw(c)

                c.save()

                if (dX > 0)
                    c.clipRect(itemView.left, itemView.top, dX.toInt(), itemView.bottom)
                else
                    c.clipRect(itemView.right + dX.toInt(), itemView.top, itemView.right, itemView.bottom)

                deleteIcon.draw(c)

                c.restore()

                super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive)
            }
        }

        val itemTouchHelper = ItemTouchHelper(itemTouchHelperCallback)
        itemTouchHelper.attachToRecyclerView(recyclerview)
    }
}

MainAdapter.kt

package heatwave.ryanaird.com.swipyrecyclerview

import android.support.constraint.ConstraintLayout
import android.support.design.widget.Snackbar
import android.support.v7.widget.RecyclerView
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView

class MainAdapter(private val dataset: MutableList<String>) : RecyclerView.Adapter<MainAdapter.MainViewHolder>() {

    private var removedPosition: Int = 0
    private var removedItem: String = ""

    class MainViewHolder(v: View) : RecyclerView.ViewHolder(v) {
        val title: TextView = v.findViewById(R.id.title)
    }

    override fun onCreateViewHolder(viewGroup: ViewGroup, viewType: Int): MainAdapter.MainViewHolder {
        val v = LayoutInflater.from(viewGroup.context)
            .inflate(R.layout.row, viewGroup, false)
        return MainViewHolder(v)
    }

    override fun onBindViewHolder(viewHolder: MainViewHolder, position: Int) {
        viewHolder.title.text = dataset[position]
    }

    fun removeItem(position: Int, viewHolder: RecyclerView.ViewHolder) {
        removedItem = dataset[position]
        removedPosition = position

        dataset.removeAt(position)
        notifyItemRemoved(position)

        Snackbar.make(viewHolder.itemView, "$removedItem removed", Snackbar.LENGTH_LONG).setAction("UNDO") {
            dataset.add(removedPosition, removedItem)
            notifyItemInserted(removedPosition)

        }.show()
    }

    override fun getItemCount() = dataset.size
}