Jon Jackson is a senior lecturer at Buckinghamshire New University and University of Surrey. For his courses, he developed a great set of YouTube videos.
There are 18 videos, anywhere from 6 to 15 minutes long. He uses AppStudio with JavaScript and Bootstrap. Topics range from Setting Up to Building a Simple Form to using Maps in Mobile Apps.
Working code is available in a GitHub repo.
It’s a great way to get started with AppStudio (and mobile app development in general) or to learn how to do new things.