I've filed a bug against this, but I'd really like to make sure this gets fixed as it is affecting all my released apps, plus many other apps that use my SVGgh rendering library.
Basically, there is a perfectly valid set of parameters that you can pass to CGPathAddArc that will cause CGPathCloseSubpath to revert the current point to the zero point. This is definitly a regression from iOS 11, and goes against the documentation of CGPathCloseSubpath. I can work around it by copying the current point before calling CGPathCloseSubpath, and then doing an explicit CGPathMoveToPoint immediately afterwards, but I'd much rather it gets fixed before release.
It's a pretty specific setup to CGPathAddArc, but as it happens it manifests itself in a simple globe graphic that I use in keyboards and other places in my apps. Which is lucky because otherwise I'd have likely missed this bug.
The bug is 42266130 if anyone at Apple is interested in following up.
