Drag and release

I need help with (what I believe to be simple but I don’t know) something (for android):
I have a 2D ball, that is on a simple square table, I want to drag from that ball and release and upon release the ball goes in that direction or in opposite direction if you drag “behind” the ball. I don’t need aim, or arrows or anything. Just put your finger on the ball then drag and release. I searched for 2 days on forums and youtube and everywhere but I couldn’t find what I need. I found something but it’s really outdated and does not help me.
Thank you for your help! And I am sorry for taking your time if there is already something answered that I didn’t find!

I found it, hope this helps someone else too!

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Swipe : MonoBehaviour {

    Rigidbody2D rbody;
    Vector2 startpos;
    Vector2 endpos;
    float power = 5f; // power of shot

    // Use this for initialization
    void Start () {

        rbody = GetComponent<Rigidbody2D>();

	// Update is called once per frame
	void Update () {


            if (Input.GetMouseButtonUp(0))
                endpos = Camera.main.ScreenToWorldPoint(Input.mousePosition);


    void OnMouseDown()
        startpos = Camera.main.ScreenToWorldPoint(Input.mousePosition);

    void LaunchBall()
        Vector2 direction = (startpos - endpos); // swap subtraction to switch direction of launch
        rbody.AddForce(direction * power, ForceMode2D.Impulse);


How can i use it with touch controls not mouse input ?