turn camera with touch unity code example

Example: turn camera with touch unity

Vector3 FirstPoint;
 Vector3 SecondPoint;
 float xAngle;
 float yAngle;
 float xAngleTemp;
 float yAngleTemp;

 void Start () {
     xAngle = 0;
     yAngle = 0;
     this.transform.rotation = Quaternion.Euler(yAngle, xAngle, 0);        
 }
 
 void Update () {
     if(Input.touchCount > 0){
         if(Input.GetTouch(0).phase == TouchPhase.Began){
             FirstPoint = Input.GetTouch(0).position;
             xAngleTemp = xAngle;
             yAngleTemp = yAngle;
         }
         if(Input.GetTouch(0).phase == TouchPhase.$$anonymous$$oved){
             SecondPoint = Input.GetTouch(0).position;
             xAngle = xAngleTemp + (SecondPoint.x - FirstPoint.x) * 180 / Screen.width;
             yAngle = yAngleTemp + (SecondPoint.y - FirstPoint.y) * 90 / Screen.height;
             this.transform.rotation = Quaternion.Euler(yAngle, xAngle, 0.0f);
         }
     }
     
 }