title: How do I make a camera follow an object in unity3d C#?
body: <p>I have an object called Ball, and I added keyboard interactivity to it(WASD to move the ball)
  I need the camera to stay behind and follow the ball, but I am getting errors.</p>
  
  <pre><code>using UnityEngine;
  using System.Collections;
  public class ballmain : MonoBehaviour {
      public bool isMoving = false;
      public string direction;
      public float camX;
      public float camY;
      public float camZ;
      // Use this for initialization
      void Start () {
          Debug.Log("Can this run!!!");
      }
  
      // Update is called once per frame
      void Update () {
          camX = rigidbody.transform.position.x -=10;
          camY = rigidbody.transform.position.y -=10;
          camZ = rigidbody.transform.position.z;
          camera.transform.position = new Vector3(camX, camY, camZ);
              //followed by code that makes ball move
      }
  }
  </code></pre>
  
  <p>I get error "Assets/ballmain.cs(18,44): error  CS1612: Cannot modify a value type return value of 'UnityEngine.Transform.position'. Consider storing the value in a temporary variable"
  Does anyone know the answer? If I comment out the code about the camera the ball can move around.</p>