As discussed earlier, iOS devices have a defined access that allows us to determine changes in the device's orientation. We can detect this as changes in the x, y, or z values in Input.acceleration:

Since our game design requires us to manipulate the camera based upon the tilt, the only step we need is to check for the direction of the orientation change and then rotate the camera accordingly. To accomplish this we can attach a script to a GameObject in whose Update() method we examine the Input.acceleration attributes and determine how the device has changed. Remember also that we have specified that our application be designed to run in landscape mode so we are looking for rotations along the device's Z-axis.

using UnityEngine;
using System.Collections;

public class CameraRotate : MonoBehaviour {
   public float speed = 10.0f;
  
   // Use this for initialization
   void Start () {   
   }
   
   // Update is called once per frame
   void Update () {
      Vector3 direction = Vector3.zero;
      direction.x = - Input.acceleration.y;
      direction.z = Input.acceleration.x;
      
      if ( direction.sqrMagnitude > 1 )
      {
         direction.Normalize();
      }
      
      direction *= Time.deltaTime;
      
      transform.Translate( direction * speed );
   }
}

With iPhoneSettings.screenOrientation we can now tell the Unity player to change its orientation. You can set the orientation to any one of the iPhoneScreenOrientations available. It is recommended that you don't do anything that would be uncharacteristic to the way the iOS device is expected to operate as Apple may reject your application for that behavior.