To access the Adobe Lightroom mobile in-app camera with a single swipe down, you can enable it using the Notification Center widget (on iOS).
Access Notifications by swiping downwards from the top of the screen. Scroll down and tap the Edit Button.
Once added, you can drag the grabber handle on the right to reorder if desired, and click Done. Lightroom mobile will now appear in the Notification Center enabling you to quickly access the in-app camera. There’s even a shortcut to edit the last photo. Enjoy!