Reachability is a network connectivity detection library for iOS and macOS that replaces Apple's standard Reachability class.
The tool solves the problem of detecting when network interfaces become available or unavailable. It modernizes Apple's original implementation by adding ARC compatibility and using Grand Central Dispatch for notifications instead of older callback mechanisms. Developers can choose between two notification approaches: NSNotification callbacks delivered on the main thread, or block-based callbacks executed on background threads. The library also allows configuration of whether WWAN connections (3G, EDGE, CDMA) should be treated as reachable, which is useful for applications like video streaming that need to enforce data-conscious behavior.
Adoption requires linking the SystemConfiguration framework and adding the header and implementation files to your project. The tool suits developers maintaining Objective-C codebases or mixed Objective-C and Swift projects who need straightforward network reachability detection. A significant caveat exists: the README warns that apps using Reachability in a framework have faced App Store rejection, with renaming the class noted as the only known workaround.
The project maintains compatibility across multiple iOS versions, with specific tags designated for older iOS releases that require different memory management patterns. The codebase remains focused on its core purpose without feature expansion beyond the core reachability detection and notification mechanisms.
