https://www.hackingwithswift.com/books/ios-swiftui/storing-user-settings-with-userdefaults

PageTabView

https://stackoverflow.com/questions/62833524/how-to-change-pagetabview-programmatically-in-ios-14-swiftui-2

ProgressView 

https://www.appcoda.com/progressview-swiftui/

RoundRectangle

https://www.appcoda.com/swiftui-unevenroundedrectangle/