If you're interested in learning more about VoiceOver, AppleVis is a great community resource for learning more about it: http://www.applevis.com

If you want to see more of it in action, you can check out the Apple Design awards, where VoiceOver engineers demo apps:

https://developer.apple.com/videos/play/wwdc2015/103/ (36:30, disclaimer: I work on this app)

https://developer.apple.com/videos/play/wwdc2016/103/ (55:45)