In reading Apple's guide on BarButtonItems, I see that several bar button icons exist which are not choosable from the Attributes inspector in Xcode (in particular the large "chevron" which appears in 4 orientations.
I've searched for a way to access them, but cannot find one. Does this mean that they are internal and only accessible to Apple's own application and I'm not permitted to use them in my own application?
This are examples for the iOS Human Interface Guidelines. So they are on this page, to show
the similarities in size, detail, and weight produce a sense of harmonious unity
Not saying, that they are available for the devs. If you want to use them anyway, you have to get and add the image files manually.
Especially the requested "chevron"s should be easily drawable.