问题
[TraitCollection] Class CKBrowserSwitcherViewController overrides the -traitCollection getter, which is not supported. If you're trying to override traits, you must use the appropriate API.
I am getting this message in debugger since I am using MFMessageComposeViewController, MFMailComposeViewController, CNContactPickerViewController in my application, and presenting them with navigation controller. My navigation controller is customized on each view controller files individually. First I tried doing the customization in app delegate "didFinishLauching" method, but that caused some problems presenting these built in controllers. But as long as I remember I was still getting the above message, when I was trying to do the latter.
回答1:
You can ignore these messages as per iOS12 Beta 2 release notes:
When running your app from Xcode, you might see console errors about UIKit classes that override the traitCollection getter. You can safely ignore these messages for system classes. If you see this error message for your own classes, it likely indicates a real issue for you to fix. (51651561)
Apple Forum Discussion Link
来源：https://stackoverflow.com/questions/58779786/class-ckbrowserswitcherviewcontroller-overrides-the-traitcollection-getter-w