C
Chris
Guest
itch.io link: https://topherlicious.itch.io/umgmd
Google Play Store link: https://play.google.com/store/apps/details?id=com.chrisanselmo.umgmd
This app has the GML reference part of the documentation completely available offline, and supports instant type-to-search and filtering. This makes it extremely convenient and straight forward to look up GML on the go. It also works well as a companion to normal development by just leaving the app open and quickly looking up what you need.
Currently, only the Android version is published but an iOS version is coming soon. When the iOS version launches, I'll update this post with the link as well as the itch.io page.
Enjoy!