Reproduction steps:
1. Crete a new Unity project.
2. Set Target SDK to Simulator SDK in 'File > Build Settings > iOS > Player Settings'.
3. Build and run the Xcode project.
4. Focus Simulator.
5. Go to 'Hardware > Orientation > Portrait'
6. Go to 'Hardware > Orientation > Landscape Right'
- Application will crash

Notes:
- Simulated device starts in a landscape mode using 2018 and in portrait using 2017 version of Unity.
- Not reproducible using physical iOS device.

Reproduced with:
2018.1.0a1 (812eca38cac1)

Not reproducible with:
2017.3.0b4 (4c1b6e48c9c9)

Call stack:
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
frame #0: 0x000000010dd2ac57 libobjc.A.dylib`objc_retain + 7
* frame #1: 0x0000000106753069 ProductName`ViewWillTransitionToSize_DefaultImpl(self_=<unavailable>, _cmd=<unavailable>, size=(width = 736, height = 414), coordinator=<unavailable>) at UnityViewControllerBase+iOS.mm:191 [opt]
frame #2: 0x000000010bb11ce3 UIKit`+[UIViewController _performWithoutDeferringTransitions:] + 114
frame #3: 0x000000010bb2b139 UIKit`-[UIViewController(AdaptiveSizing) _window:viewWillTransitionToSize:withTransitionCoordinator:] + 931
frame #4: 0x000000010b9deca4 UIKit`__59-[UIWindow _rotateToBounds:withAnimator:transitionContext:]_block_invoke + 178
frame #5: 0x000000010b9deadf UIKit`-[UIWindow _rotateToBounds:withAnimator:transitionContext:] + 394
frame #6: 0x000000010b9e18d6 UIKit`-[UIWindow _rotateWindowToOrientation:updateStatusBar:duration:skipCallbacks:] + 1859
frame #7: 0x000000010b9e230c UIKit`-[UIWindow _setRotatableClient:toOrientation:updateStatusBar:duration:force:isRotating:] + 709
frame #8: 0x000000010b9e10d2 UIKit`-[UIWindow _setRotatableViewOrientation:updateStatusBar:duration:force:] + 123
frame #9: 0x000000010b9dfc34 UIKit`__57-[UIWindow _updateToInterfaceOrientation:duration:force:]_block_invoke + 112
frame #10: 0x000000010b9dfac2 UIKit`-[UIWindow _updateToInterfaceOrientation:duration:force:] + 485
frame #11: 0x000000010e3e307c CoreFoundation`__CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 12
frame #12: 0x000000010e3e2f7a CoreFoundation`_CFXRegistrationPost + 442
frame #13: 0x000000010e3e2cc2 CoreFoundation`___CFXNotificationPost_block_invoke + 50
frame #14: 0x000000010e3a4a32 CoreFoundation`-[_CFXNotificationRegistrar find:object:observer:enumerator:] + 1826
frame #15: 0x000000010e3a3bac CoreFoundation`_CFXNotificationPost + 652
frame #16: 0x000000010a7ad842 Foundation`-[NSNotificationCenter postNotificationName:object:userInfo:] + 66
frame #17: 0x000000010bd5c87d UIKit`-[UIDevice setOrientation:animated:] + 290
frame #18: 0x000000010c402260 UIKit`__124-[_UICanvasDeviceOrientationSettingsDiffAction _updateDeviceOrientationWithSettingObserverContext:canvas:transitionContext:]_block_invoke + 85
frame #19: 0x000000010c564eb0 UIKit`_performChangesWithTransitionContext + 613
frame #20: 0x000000010c4021d9 UIKit`-[_UICanvasDeviceOrientationSettingsDiffAction _updateDeviceOrientationWithSettingObserverContext:canvas:transitionContext:] + 250
frame #21: 0x000000010c40206c UIKit`__133-[_UICanvasDeviceOrientationSettingsDiffAction performActionsForCanvas:withUpdatedScene:settingsDiff:fromSettings:transitionContext:]_block_invoke + 112
frame #22: 0x000000010c564c3e UIKit`_performActionsWithDelayForTransitionContext + 100
frame #23: 0x000000010c401fb8 UIKit`-[_UICanvasDeviceOrientationSettingsDiffAction performActionsForCanvas:withUpdatedScene:settingsDiff:fromSettings:transitionContext:] + 173
frame #24: 0x000000010c0eaa4c UIKit`-[_UICanvas scene:didUpdateWithDiff:transitionContext:completion:] + 392
frame #25: 0x000000010bf29a24 UIKit`-[UIApplicationSceneClientAgent scene:handleEvent:withCompletion:] + 509
frame #26: 0x0000000111015bbb FrontBoardServices`__80-[FBSSceneImpl updater:didUpdateSettings:withDiff:transitionContext:completion:]_block_invoke.362 + 205
frame #27: 0x000000010f53f2b5 libdispatch.dylib`_dispatch_client_callout + 8
frame #28: 0x000000010f544565 libdispatch.dylib`_dispatch_block_invoke_direct + 324
frame #29: 0x0000000111049672 FrontBoardServices`__FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 24
frame #30: 0x0000000111049328 FrontBoardServices`-[FBSSerialQueue _performNext] + 464
frame #31: 0x0000000111049897 FrontBoardServices`-[FBSSerialQueue _performNextFromRunLoopSource] + 45
frame #32: 0x000000010e3ea2b1 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
frame #33: 0x000000010e489d31 CoreFoundation`__CFRunLoopDoSource0 + 81
frame #34: 0x000000010e3cec19 CoreFoundation`__CFRunLoopDoSources0 + 185
frame #35: 0x000000010e3ce1ff CoreFoundation`__CFRunLoopRun + 1279
frame #36: 0x000000010e3cda89 CoreFoundation`CFRunLoopRunSpecific + 409
frame #37: 0x000000010e9ae9c6 GraphicsServices`GSEventRunModal + 62
frame #38: 0x000000010b963d30 UIKit`UIApplicationMain + 159
frame #39: 0x0000000106752402 ProductName`main(argc=1, argv=0x00007fff594ae228) at main.mm:33 [opt]
frame #40: 0x000000010f5b3d81 libdyld.dylib`start + 1
frame #41: 0x000000010f5b3d81 libdyld.dylib`start + 1