Setting up the project
In this chapter, we are once again dealing with two apps in parallel, one for watchOS and one for iOS (which has been coded for you, but we will refer to it frequently). All but one of the files (SharedConstants.swift) will be used by one target (that is, one of the apps) or the other, and we must ensure that these targets are correctly selected for each file that we create within the project.
Create the required watchOS classes
We will begin by creating the Swift files that we will need. Once this is done, you will have a good overview of the overall structure of the project and an idea of how the pre-coded iOS files relate to the watchOS app you will be writing.
In the project navigator, select the On Q WatchKit Extension group so that the files we create below will automatically select the WatchKit target in the file creation dialog (where we selected both the On Q and On Q WatchKit Extension targets above) and then perform the following steps:
Create a new Swift file...
