iOS Hotspot Network SubSystem

The hotspot network subsystem allows a hotspot helper application to participate in the process of classifying and authenticating to Wi-Fi hotspots. A hotspot helper application can receive commands and provides a responses to a command once it has been processed. In most instances application command processing occurs while application is running in the background. 

The application receives command to process as part of two main functions: authentication and scan list filtering. 

References:

https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/Hotspot_Network_Subsystem_Guide/Contents/Introduction.html#//apple_ref/doc/uid/TP40016639-CH1-SW1