Thanks all who have replied. I just started with coding in general and found the Swift Playgrounds "Everyone can code" (Mac or iPad) a nice and playful start. If you directly want to start, Apple also has a "Develop in Swift" series. You find all of it on the "Teaching Code" - https://www.apple.com/education/k12/teaching-code/ page at Apple.
Be aware that Xcode (and Swift) do change over time, I found it easiest to use resources that were developed for that version of Xcode.