NullReferenceException: Object reference not set to an instance of an object [Camera Moving Setting for Android]

Hey Guys,

I am newbie in Unity.

I have a problem when I would implement the moving camera for Android with touching the screen.

When I start in unity, directly the camera [instance] in the inspector is missing and it shows "NullReferenceException: Object reference not set to an instance of an object TouchCameraControl.Update () (at Assets/Scripts/TouchCameraControl.cs:28)"

I am really looking for the insight from all of you guys.

" using UnityEngine; using System.Collections;

// touch camera control public class TouchCameraControl : MonoBehaviour { public float moveSensitivityX = 1.0f; public float moveSensitivityY = 1.0f; public bool updateZoomSensivitiy = true; public float orthoZoomSpeed = 0.05f; public float minZoom = 1.0f; public float maxZoom = 20.0f; public bool invertMoveX = false; public bool invertMoveY = false;

 public Camera cam;
 
 void Start()
 {
     cam = Camera.main;
 }

 // update the mouse sensitivity
 void Update()
 {
     if(updateZoomSensivitiy)
     {
         moveSensitivityX = cam.orthographicSize / 5.0f;
         moveSensitivityY = cam.orthographicSize / 5.0f;
     }
     
     Touch[] touches = Input.touches;
     
     if(touches.Length > 0) // to validate the length of touches in screen
     {
         // single touch (move)
         if(touches.Length == 1)
         {
             if(touches[0].phase == TouchPhase.Moved)
             {
                 Vector2 delta = Input.touches[0].deltaPosition; // difference between the touch position of current frame and the touch position of previous frame
                 
                 float positionX = delta.x * moveSensitivityX * Time.deltaTime;
                 positionX = invertMoveX ? positionX : positionX * - 1;
             
                 float positionY = delta.y * moveSensitivityY * Time.deltaTime;
                 positionY = invertMoveX ? positionY : positionY * -1;
             
                 cam.transform.position += new Vector3(positionX, positionY, 0);
             }  
         }
         
         // double touch (zoom)
         if(touches.Length == 2)
         {
             Touch touchOne = touches[0];
             Touch touchTwo = touches[1];
             
             Vector2 touchOnePrevPos = touchOne.position - touchOne.deltaPosition;
             Vector2 touchTwoPrevPos = touchTwo.position - touchTwo.deltaPosition;
         
             float prevTouchDeltaMag = (touchOnePrevPos - touchTwoPrevPos).magnitude;
             float touchDeltaMag = (touchOne.position - touchTwo.position).magnitude;
             
             float deltaMagDiff = prevTouchDeltaMag - touchDeltaMag;
             cam.orthographicSize += deltaMagDiff * orthoZoomSpeed;
             cam.orthographicSize = Mathf.Clamp(cam.orthographicSize, minZoom, maxZoom);
         }
     }
 }

}

"

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