仅移动对象触摸屏幕

Question

当用户触摸屏幕并从屏幕上移开手指时，我将对象上移，

当用户触摸屏幕并按住手指在屏幕上时，我将对象移到右。

问题是，如果用户将手指从屏幕上移开，则对象仍在移动。

void FixedUpdate()
    {
        // Detect the first click
        if (Input.GetMouseButtonDown(0))
        {
            totalDownTime = 0;
            clicking = true;    
        }

        // If a first click detected, and still clicking,
        // move object right
        if (clicking && Input.GetMouseButton(0))
        {
            totalDownTime += Time.deltaTime;
            rigidBody.velocity = Vector2.zero;
            if (totalDownTime >= 0.5f)
            {

                clicking = false;
                OnLongClick.Invoke();
                rigidBody.AddForce(Vector2.right * 200, ForceMode2D.Force);

            }
        }

        // If a first click detected, and we release before the
        // duration, move object up
        if (clicking && Input.GetMouseButtonUp(0))
        {
            rigidBody.AddForce(Vector2.up * tapForce, ForceMode2D.Force);
            clicking = false;
        }
    }

如何仅在触摸屏幕时移动对象？