Philips discontinued their official Hue SDK framework for iOS, and as a result we have removed it in Luminair 4 and replaced it with native Apple HomeKit support. HomeKit allows you to control Hue lights alongside any other HomeKit manufacturer's lights.
To upgrade, first add your Hue bridge (v2 or later) to a HomeKit Home within the Home app on your device. You will need to create a Home first if you haven't already.
Once the bridge has been added to the Home, Luminair can then connect via Apple's HomeKit API.
When opening a project with Hue lights, Luminair will attempt to detect and convert them. Please make sure that lights are named the same to ensure they're discovered correctly. You can also manually change smart light assignments in the Connections view > HomeKit.
More information about adding lights from HomeKit are available in this article.