Is it possible to display the list of available wi-fi in the application and then user could join any one of them from the application itself?
I know that prior to iOS 9, it was not possible. But with changes in iOS9, I am not sure. Why is NSHotspotHelper class? Does this class has something to do with my queries?
No. This is still not possible. If you're interested in wi-fi related restrictions (access is actually more restricted in iOS 9), then have a look at this thread: https://forums.developer.apple.com/thread/11807