I’m still not sure what you mean by “lessons on many code languages”.
There is only one programming language used in the Apple integrated development environment known as “Xcode” and that language is “Swift”. The language is used in the framework known as UIKit and also in the new framework (new as of 2019) called SwiftUI.
The codewithchris App on the App Store concentrates on the 14 Day Beginner Challenge which is based on the SwiftUI framework given that SwiftUI is the future of programming under the Xcode environment. It still uses the Swift programming language.