Bundles in Your Swift Project Code
A bundle identifies your target — that is, the app that you’re building in Swift. That’s the basic definition. The bundle identifier is constructed automatically by Xcode from your organization identifier and your product identifier. The combination of the two should be unique, and it will be if you use the reverse domain name of your company or organization as the organization name.
Behind the scenes your bundle identifier is further modified by having your developer identifier prepended to it. Although the bundle identifier is used to identify your app, this is a bit of a generalization. For iCloud‐enabled apps, several apps can share one bundle identifier for their common iCloud storage.
A bundle identifier is key to identifying your app behind the scenes. It is not a user‐facing name, although your product name is included as part of the bundle name. Furthermore, be aware that you can modify almost every step of the process to create your own naming conventions.