Before we can begin adding and using glances within our Shopping List application, we need to get a better understanding of how they work within the WatchKit framework. We did talk a bit about this in an earlier chapter, Chapter 2, Understanding Apple Watch, so much of this will be quite similar.
In the next section, we will talk a bit about the glance controller life cycle, and you will note that the glance controller inherits all of the existing functionalities of the WKInterfaceController class and contains a variety of methods and calls that help determine whenever a glance becomes active or the controller context instance becomes awake.