Core Location - Significant Location Updates Requires Background Permissions

If you've watched the WWDC video you will already know this but if you just look at the class references it isn't obvious that . iOS 8 introduced the possibility to request permission to access location only while the App is in the foreground which should encourage users to grant permission without fear of being tracked inappropriately however the foreground only mode only works with some of the modes. This slide from the talk (WWDC 2014 What's New In Core Location - Session 706) is the key one: