APPCELERATOR CLOUD SERVICES comes with a robust set of predefined objects, many of which you have used already to build your application. The next one you will use is the Friends object. This object allows you to create relationships between users so you can create followers just like with Facebook and Twitter. In the application you are building, you will allow the users of the application to select users to follow so they can view pictures of all of the people they follow. The pictures will automatically be added to the feed.
In this chapter, you will create new models, views, and controllers to support the Friends functionality and also update other areas of the application to support the Friends functionality. See http://docs.appcelerator.com/cloud/latest/#!/api/Friends.
Before you get started with friends and followers, you need to create a library to provide the activity indicator. This will let users know that there is some sort of network or long activity happening and that the application is not locked up. This also gives you an opportunity to see how CommonJS libraries can be integrated into your application, potentially repurposing old non-Alloy-based code that you believe is still valuable in your development toolset.
Go to the folder app/ lib; in that directory, create a new file called progressWindow.js.