I have built several apps using autolayout and individual xib files. In Xcode 9, there is no option for 'Use safe area layout guides' for xib files, just Storyboards.
How do I adjust my existing constraints to work for the new device?
No safe area options for Xib files?!
I think it is properly explained here. In IOS11,
in iOS 11, the top and bottom layout guides are deprecated and replaced with a single safe area layout guide.
h ttps://useyourloaf.com/blog/safe-area-layout-guide/
See also this other thread and KMT answer :
h ttps://forums.developer.apple.com/thread/79400
I have seen that information. That is the case if you are using storyboards. If you have a xib file outside of a storyboard, there is no option to use those features.
Click on something in the xib and "Use Safe Area Layout Guides" will be accessible under the document properties for the xib. For some reason you need to do that. From there you can proceed as with a storyboard.