The Design+Code iOS app lets you read and watch 44 hours of content about the techniques involved in making this app, using tools like Sketch, Framer and Xcode 9. You can bookmark important parts, check your progress for each section and do exercises to strengthen your knowledge. Zero coding experience required. Perfect for visual people.
Periphery is a developer tool that identifies unused code in Swift projects. It's thorough, accurate, and can identify many non-obvious scenarios of unused code.