ScrollRectExtension.cs

using UnityEngine;
using UnityEngine.UI;

namespace Prototype.Scripts.Utils
{
    public static class ScrollRectExtension
    {
        public static void SnapToChild(this ScrollRect scrollRect, RectTransform child)
        {
            scrollRect.content.localPosition = GetContentLocalPositionForChild(scrollRect, child);
        }

        public static void SnapToChildLocalPosition(this ScrollRect scrollRect, Vector2 childLocalPosition)
        {
            scrollRect.content.localPosition = GetContentLocalPositionForChild(scrollRect, childLocalPosition);
        }

        /// <summary>
        /// Get position, which will bring to center child element
        /// </summary>
        /// <param name="scrollRect"></param>
        /// <param name="child"></param>
        /// <returns></returns>
        public static Vector2 GetContentLocalPositionForChild(this ScrollRect scrollRect, RectTransform child)
        {
            return GetContentLocalPositionForChild(scrollRect, child.localPosition);
        }
    public static Vector2 GetContentLocalPositionForChild(this ScrollRect scrollRect, Vector2 childLocalPosition)
        {
            Canvas.ForceUpdateCanvases();

            Vector2 viewportLocalPosition = scrollRect.viewport.localPosition;

            Vector2 result = new Vector2(
                0 - (viewportLocalPosition.x + childLocalPosition.x),
                0 - (viewportLocalPosition.y + childLocalPosition.y));

            return result;
        }
    }
}