Free resources

Looks good but you might find some very dated stuff in there. I just checked the iOS one and it's based on XCode 8.3.3 which was released back in 2017. The recipes may be relevant but they won't be plug-and-play and if you're really looking to learn you're better off with more recently updated courses from the likes of Udemy, and the free Stanford course on YouTube that include things like SwiftUI

If I remember correctly, these are based on the Stack Overflow Documentation Project that had shutdown back in 2017. Documentation on frameworks or tools that aren't changing as frequently are probably still relevant today, but given how fast things move in some industries (e.g., web frameworks, mobile), some of it is likely becoming too dated to be useful.