Usage in an extension

[andrewvmail]

Getting this when trying to use inside an extension
'shared' is unavailable in application extensions for iOS: Use view controller based solutions where appropriate instead.

I comment out everything in that function and it compiles fine

    func tick() {
//        let previousValue = UIApplication.shared.isNetworkActivityIndicatorVisible
//        let newValue = (runningRequests > 0)
//        if newValue != previousValue {
//            UIApplication.shared.isNetworkActivityIndicatorVisible = newValue
//        }
    }