TransformHelper.cs

using UnityEngine;
using System.Collections;

public class TransformHelper
{

    public static Transform FindChild(Transform parent, string goName)
    {
        var child = parent.Find(goName);
        if (child != null) return child;

        for (int i = 0; i < parent.childCount; i++)
        {
            child = parent.GetChild(i);
            var go = FindChild(child, goName);
            if (go != null) return go;
        }
        return null;
    }

    public static void LookAtTarget(Vector3 targetDir, Transform transform,
        float rotationSpeed)
    {
        if (targetDir != Vector3.zero)
        {
            Quaternion targetRotation = Quaternion.LookRotation(targetDir);
            transform.rotation = Quaternion.Lerp(transform.rotation,
             targetRotation, rotationSpeed);
        }
    }
}