// By Name
GameObject Child = GameObjectsTransform.Find("NameOfChild").gameObject
// By index
GameObject Child = GameObjectsTransform.GetChild(The child index).gameObject
GameObject Child;
Child = transform.GetChild(0).gameObject;
//with the index
parentGameObject.transform.GetChild(0).gameObject
//or with the name
parentGameObject.transform.GetChild("name").gameObject
//Instantiate Prefab
GameObject originalGameObject = Instantiate(prefab);
//To find `child1` which is the first index(0)
GameObject child2 = originalGameObject.transform.GetChild(0).gameObject;
//To find `child2` which is the second index(1)
GameObject child2 = originalGameObject.transform.GetChild(1).gameObject;
//To find `child3` which is the third index(2)
GameObject child3 = originalGameObject.transform.GetChild(2).gameObject;
//For unity engine
GameObject.transform.GetChild(The child index).transform;
GameObject originalGameObject = GameObject.Find("MainObj");
GameObject child = originalGameObject.transform.GetChild(0).gameObject;
Transform[] transforms = this.GetComponentsInChildren<Transform>();
foreach(Transform t in transforms)
{
if (t.gameObject.name == "Child")
{
Debug.Log ("Found " + t);
}
}