GridRecyclerView.kt

class GridRecyclerView : RecyclerView {
    private lateinit var manager: GridLayoutManager
    private var columnWidth = -1

    constructor(context: Context) : super(context) {
        init(context, null)
    }

    constructor(context: Context, attrs: AttributeSet?) : super(context, attrs) {
        init(context, attrs)
    }

    constructor(context: Context, attrs: AttributeSet?, defStyle: Int) : super(context, attrs, defStyle) {
        init(context, attrs)
    }

    private fun init(context: Context, attrs: AttributeSet?) {
        if (attrs != null) {
            val attrsArray = intArrayOf(
                android.R.attr.columnWidth
            )
            val array = context.obtainStyledAttributes(attrs, attrsArray)
            columnWidth = array.getDimensionPixelSize(0, -1)
            array.recycle()
        }
        manager = GridLayoutManager(getContext(), 1)
        layoutManager = manager
    }

    override fun onMeasure(widthSpec: Int, heightSpec: Int) {
        super.onMeasure(widthSpec, heightSpec)
        if (columnWidth > 0) {
            var spanCount = 1.coerceAtLeast(measuredWidth / columnWidth)
            //we need at least 2 columns
            if (spanCount == 1) spanCount = 2
            manager.spanCount = spanCount
        }
    }

    /**
     * Item decoration
     */
    class ItemDecoration(context: Context, @DimenRes marginDimenId: Int) : RecyclerView.ItemDecoration() {
        private val margin: Int = context.resources.getDimensionPixelSize(marginDimenId)

        override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: State) {
            outRect[margin, margin, margin] = margin
        }

    }
}