view controller not dismissed

When you unwind, you dismiss the view controller you come from.

if you unwind from 3 -> 1, controller 2 will still exist, controller 3 is dismissed

if you segue again to controller2, you'll create a new (second) instance. So you should take care

Here is a discussion about this "problem"

h ttps://stackoverflow.com/questions/8311323/it-is-possible-to-use-an-existing-viewcontroller-with-performseguewithidentifier

I found also this interesting to better understand how it works:

h ttps://developer.apple.com/library/content/technotes/tn2298/_index.html

h ttps://stackoverflow.com/questions/12561735/what-are-unwind-segues-for-and-how-do-you-use-them