I was using prefs:root=WIFI url scheme in my app with prefs entered in info.plist to open directly the iOS settings application in Wi-Fi settings and it was working great on iOS 9 but it does not work anymore on iOS 10.
Does anyone know if this is just a regression in the first developer preview or the way to open Wi-Fi settings has changed in iOS 10 or it is not allowed anymore?
Just so it's explicit: Apple does not allow this. It's possible your app will make it through anyway, but this is the same as using any other undocumented API.
Here is the full list of supported Apple URL schemes.
Here's a thread where Apple confirms that "any Apple URL schemes that are not officially documented should be considered private API."