Spawning GameObjects with Hinge Joints

hi sir, am facing problem on adding hinge joint to my prefab. what my project i need to create rope that was dynamically increasing and decreasing when we press up and down arrows. what am doing is

//instantiating a prefab

clone = (GameObject)Instantiate (obj, current.transform.position, Quaternion.identity);

//storing the prefab into a list

         instantlist.Add(clone);
         instantlist[instantlist.Count-1].name="clone"+instantlist.Count;

//adding hinge joint

clone.AddComponent(); clone.GetComponent

//assaign position

         clone.transform.position = new Vector3 (current.transform.position.x, current.transform.position.y+1f , current.transform.position.z);
         current = clone.gameObject.transform;
 

Another option is to use a Rigid Body (IsKinematic=true) as parent and set the Connected Rigid Body property to this. Spawning the parent keeps the Connected Anchor in place and it works without any glitches. I found this solution on https://stackoverflow.com/questions/22845379/unity-spawning-gameobjects-with-hinge-joints