Lynda - Building an App for All Apple Platforms

https://www.lynda.com/iOS-tutorials/Building-App-All-Apple-Platforms/2841535-2.html
Each Apple platform—macOS, iOS, iPadOS, watchOS and tvOS—offers individual capabilities and user experience, yet also integrates tightly to provide a unified feel. In this project-based course, learn how to build an app that will not only run seamlessly across all Apple platforms, but also fit the specific function and UX of each device. In a sample project, discover how to set up a multiplatform template and build user interfaces leveraging a single set of tools and APIs. Consider different navigation requirements for iPhone, iPad, and Mac, and explore the design principles particular to each one. Plus, discover how to write platform-specific and independent code.