Swift 利用Reachability监测网络连接

 class ReachabilityHelper {
 static func reach(_ reachable: @escaping (_ wifi:Bool) -> Void, unreachable: @escaping () -> Void) {
 
 
    let reachability = Reachability()!
    
    reachability.whenReachable = { reachability in
        // this is called on a background thread, but UI updates must
        // be on the main thread, like this:
       DispatchQueue.main.async {
            if reachability.isReachableViaWiFi {
 
 
// print("Reachable via WiFi")
 reachable(true)
 } else {
 // print("Reachable via Cellular")
 reachable(false)
 }
 
 
        }
    }
    reachability.whenUnreachable = { reachability in
        // this is called on a background thread, but UI updates must
        // be on the main thread, like this:
        DispatchQueue.main.async {
 
 
// print("Not reachable")
 unreachable()
 }
 
 
    }
    
    do {
        try reachability.startNotifier()
    } catch {
 
 
// print("Unable to start notifier")
 }
 }
 
 
}