We've covered the basics up to functions, and now I'll provide exercises that review topics from all of those chapters.
The intended audience for this guide are people that don't know Swift and possibly don't know any other programming language.
When you make GUI tests using XCUI directly in Xcode, it will automatically build the app for you when you run the test. Appium, however, is run completely outside of Xcode, so you must supply a build for it.
If you are considering Appium or any other GUI testing framework for iOS, like XCUI Tests, then the first thing you should do is start using accessibility identifiers. Without them, your test scripts will be much more brittle.