CODE EXAMPLE FOR CSHARP

C# Move Camera Over Terrain Using Touch Input In Unity 3D - Append To Camera

private Vector2 worldStartPoint;

void Update () {

    // only work with one touch
    if (Input.touchCount == 1) {
        Touch currentTouch = Input.GetTouch(0);

        if (currentTouch.phase == TouchPhase.Began) {
            this.worldStartPoint = this.getWorldPoint(currentTouch.position);
        }

        if (currentTouch.phase == TouchPhase.Moved) {
            Vector2 worldDelta = this.getWorldPoint(currentTouch.position) - this.worldStartPoint;

            Camera.main.transform.Translate(
                -worldDelta.x,
                -worldDelta.y,
                0
            );
        }
    }
}

// convert screen point to world point
private Vector2 getWorldPoint (Vector2 screenPoint) {
    RaycastHit hit;
    Physics.Raycast(Camera.main.ScreenPointToRay(screenPoint), out hit);
    return hit.point;
}