Note: This is the second entry in a series of posts about writing my first iOS app. The app is currently in review, and until it is rejected or approved, I plan to write something every day about what I’ve learned.
In my first post, I talked about how I decided to use Core Data to store the verses in my Bible verse app and how I went about seeding that database. The next thing I had to figure out was how in the world my Watch app and iOS app could access the same Core Data model. I learned from a Make & Build tutorial that I needed to create both an App Group and a custom framework that could be shared between the two apps.
After creating a framework, I added two files to it: my Verse class, and a singleton DataManager class that handles all of the Core Data methods. Singletons are still a little confusing to me, so I pretty much just copied the code from this excellent tutorial video. At first I couldn’t figure out why my apps couldn’t seem to “see” anything in the framework, even after linking to it. Then I realized that I forgot to mark everything in the framework as “public.” /facepalm
My DataManager class has three simple methods: a method to fetch all of the verses in the store and place them in an array, a method to fetch only verses marked as a favorite, and a method to select a random verse from the array. Using one of the methods in my WatchKit app was as easy as saying:
var verse:Verse = DataManager.sharedInstance.getRandomVerse(verses)
Tomorrow, I’ll either talk about my app’s visual style (colors, icon, name, etc.), or about Glances and using Handoff.