Reachability
ARC and GCD Compatible Reachability Class for iOS and MacOS
Reachability is a lightweight Objective-C wrapper around Apple’s SCNetworkReachability that reports whether the network is reachable and via which interface (Wi-Fi or cellular). It exposes both notifications and blocks so you can react to connectivity changes without polling. Typical usage is to gate network requests, disable online-only UI, and show graceful messaging when connectivity drops. The implementation is careful about threading and runloop scheduling so events arrive reliably...