There is a famous site called Developer Roadmaps, which suggests skill roadmaps for web front end, back end, Android, etc. as a diagram.
However, there is no iOS version. .. ..
When I searched for it, I found that a relatively good thing was posted on an American posting SNS called "Reddit".
Quote: 2018 Roadmap to iOS Development
Maybe because it was written a few years ago There are some things I want to do, such as "Objective-C doesn't have to be mandatory ...", but ...
Other than that,
** "As you learn the skills on the yellow background, you will reach the point as an iOS engineer." ** From this point of view, I thought I could generally agree.
By the way, it's ironic to Apple that there is an item called "Lucky Reviewer" in the Pick any category in the last App Store section (laughs).