When Apple announced iOS 10 and macOS Sierra at its WWDC keynote yesterday, it hit most of the high notes. Big user-facing features like the Siri API on iOS and Siri on the Mac, the revamped Messages app, Universal Clipboard, and tweaks to Photos and Apple Music got stage time, but as the company said, there was more stuff that didn’t get any attention.
Our previews and reviews of the beta and final versions of the OSes will cover all of those features and lots of the smaller, less notable tweaks to Apple’s built-in apps, but, after a few hours of digging through the developer documentation, we’ve also unearthed a few neat under-the-hood tweaks in both Sierra and iOS 10.
iCloud syncing without the Mac App Store
Can someone check the Mac App Store’s pulse? I’m worried about it.
iCloud API support was one of the carrots that Apple has offered to developers in the Mac App Store as a way of compensating for the sandboxing stick. Sierra removes that particular requirement; now, any app signed with a valid Developer ID can use CloudKit, iCloud Keychain, iCloud Drive, push notifications, MapKit, and VPN entitlements in their apps.
This will hopefully increase the extent to which these features are used in OS X apps, as well as provide some cloud infrastructure to independent developers who want to offer cloud storage and other services without dealing with the Mac App Store. None of it is available for unsigned apps, though, and anyone developing unsigned apps (or using unsigned code or disk images alongside a signed app) will have more hoops to jump through in Sierra.
Gatekeeper tweaks

Since it was introduced in Mountain Lion, the Gatekeeper security feature in OS X has always offered an option to completely disable it. In the first Sierra beta, this is no longer the case—you can let your Mac run only apps from the Mac App Store or App Store apps along with properly signed apps from outside the App Store (the latter is the default, as it has been since the feature was introduced).