My friend and I are planning to use Swift to develop an application for our computer science class. I know there is a $99 fee for being an Apple developer but I was confused as to exactly where this applies. The Swift language itself is open source and downloadable through Xcode. If we were to just create the application but not place it on the App Store for purchase, do we still have to pay the $99?
The $99 fee is only if you want to publish apps to the App Store. You can download all the latest release versions of the development tools and create your own apps without paying anything.
The Development account also allows you access to the private beta versions of Apple's operating systems and development tools, so if you wanted the latest beta of watchOS, iOS, macOS or tvOS, you would need to pay the $99.
In addition, the free developer account has several limitations. The free account limits the number of devices (3) you can distribute the app on, the number of apps (3) per device, the number of days that the app will remain functional (7) and the number of app IDs(10) created in one week. These limits are subject to change at any time. The free account is fine to develop with but if you want to use your apps for more than a week then you will need a paid developer account.