It looks like several people have problems with crashes after updating their iOS exporter to the new beta.
So far almost all issues have been caused by XCode caching old files.
When you update your iOS exporter and export a new XCode project please follow these steps to ensure everything is correct:
- Delete your app from your device and/or iOS simulator
- In XCode go to "Products -> Clean" to clean out all cached files
- Rebuild your project again
Thanks!