Workaround for Unity set Screen.orientation bug on iOS 10.

ForceLandscape.cs

using UnityEngine;
using System.Collections;

// This is used to workaround https://issuetracker.unity3d.com/issues/ios-changing-the-screen-orientation-via-a-script-sometimes-results-in-corrupted-view-on-ios-10
// Bug shows screen in portrait with content rotated 90 offscreen. Caused by explicitly setting Landscape orientation on iOS 10.
// 
// On iOS this just switches to LandscapeLeft, back to Portrait, and then back to LandscapeLeft, which seems to work.
// SUGGESTION: blank out the screen before executing this, since the screen jumps around as it switches back and forth.
public class ForceLandscape : MonoBehaviour
{
    public void ForceLandscapeLeft()
    {
        #if UNITY_IOS && !UNITY_EDITOR
        StartCoroutine(ForceAndFixLandscape());
        #else
        Screen.orientation = ScreenOrientation.LandscapeLeft;
        #endif
    }

    IEnumerator ForceAndFixLandscape()
    {
        ScreenOrientation prev = ScreenOrientation.Portrait;
        for (int i = 0; i < 3; i++)
        {
            Screen.orientation = 
                (prev == ScreenOrientation.Portrait ? ScreenOrientation.LandscapeLeft : ScreenOrientation.Portrait);
            yield return new WaitWhile(() => {
                return prev == Screen.orientation;
            });
            prev = Screen.orientation; 
            yield return new WaitForSeconds(0.5f); //this is an arbitrary wait value -- it may need tweaking for different iPhones!
        }
    }
    
}

This is used to workaround https://issuetracker.unity3d.com/issues/ios-changing-the-screen-orientation-via-a-script-sometimes-results-in-corrupted-view-on-ios-10
Bug shows screen in portrait with content rotated 90 offscreen. Caused by explicitly setting Landscape orientation on iOS 10.

On iOS this just switches to LandscapeLeft, back to Portrait, and then back to LandscapeLeft, which seems to work.
SUGGESTION: blank out the screen before executing this, since the screen jumps around as it switches back and forth.