It's free course which has been created by Paul Hadson. It's a new version (SwiftUI) of 100 Days Of Swift (which uses UIKit)
Footnote: The all "100 Days" series serve one purpose: "Making a habit". So, this course gives you a habit at Swift and that's also why I used Paul's course to learn.
for more information (also for getting started) https://www.hackingwithswift.com/100/swiftui
