There are a lot of things you can be doing to prepare yourself to learn iOS development with DevMountain. They include, but are not limited to, the following:
Get a taste for iOS technologies like Swift and Xcode, and practice! There are a lot of different resources students have used in the past to start learning: www.teamtreehouse.com, https://github.com/DevMountain/learn-ios
More important than understanding how everything works, is knowing that you can be passionate about it. A passion for the work makes all the difference in being able to focus and commit to what it takes to be a successful developer.
Make arrangements to dedicate the necessary time for the course. Full-time Immersive courses are made up of 40 to 60 hours of required pre-course work (readings and exercises that need to be completed before class starts) 40 class hours/week, and 10 to 20 hours outside of class on project work and practice.