How to avoid pitfalls and bad Stack Overflow code when handling UI gestures on iOS! — With the iPhone X out now, more and more navigation is by swiping rather than using buttons.
I presented this on 2018/09/15 at the Tokyo iOS Meetup in Shibuya: https://www.meetup.com/TokyoiOSMeetup/
This second half of this presentation is an extension of a blog post I wrote, which has links to the code: https://benguild.com/2018/09/03/simple-pull-to-dismiss-uiscrollview-swift/