MobileApplication.MajorVersion
From Xojo Documentation
Read-Only Property (As Integer )
The version to be incremented when the release includes many large new features.
Notes
This can only be set in the IDE, but you can read the value in your code.
Typically version numbers are written as 1.2.3.4 (MajorVersion.MinorVersion.BugVersion.NonReleaseVersion).
Sample Code
Puts all the individual versions together to create the full version: