Imho, video is the best medium for learning to program, but sometimes a trusted good book as reference could be precious (so I could stop taking notes in Swift playgrounds while watching your courses!).Would you like to write one, or in your opinion there are enough decent books and resources online and there's no need for more / you wouldn't enjoy writing one?
I wrote a couple of books (and contributed / tech edited several more) about ten years ago. While I liked having stuff in print and on the shelves - it's nice to see your own book in a bookstore - the downsides were significant.
Mainly, it takes such a long time - both to write, and then to get through the publishing process - that you'd rarely want to figure out what your hourly rate was as an author. Most folks who write technical books should do it for the intangible benefits (credibility, etc.).
Sure, there are ways to improve the process (self publishing, creating iBooks, etc.) but you're often then excluding what *does* make technical book writing useful - having a real editor, having a technical editor.
Having said all that, at least once or twice a year I toy with the idea, and at some point I expect I'll write again - just not in a rush to do it quite yet.