So I'm getting started in windows store apps. It is also my first experience with Visual Studio. Windows 8.1 for that matter, too :P
I'm trying to figure out how local file storage works during the dev phase of this project. I understand the concept of how the appdata directory and the application install directory interact with the app once it is published and installed on a client's PC. This SO answer gives a good overview of how it is supposed to work. However, I can't figure out how, during development, I am supposed to use these concepts if the app isn't installed and doesn't have a dedicated folder in any of the appdata directories.
Any help is much appreciated!
As others have pointed out, the app will be installed locally and the app's data will reside in some common place like C:\Users\YourUserName\AppData\local\packages during development. Check with the Packaging tab of your Package.appxmanifest file to determine the Package family name, it's probably going to be something cryptic. There'll be a corresponding folder in the packages folder.
One additional thing, though. There's a difference between an app that's been installed from an .appx file (e.g., through the store or side-loaded onto a device), and the type of installation that Visual Studio will perform for you when debugging. The latter is a so-called "unpackaged installation", and the application files that are part of your app package will be laid out slightly differently, with different implications. Most importantly, you will be able to modify the contents of files in your app package, which will fail for the same app when installed from an .appx. Also, you won't be able to install a packaged version of an app if an unpackaged install is present on the machine. (Of course, files in the AppData folder will behave the same way in either case.)