NetworkMonitor.swift

enum NetworkStatus {
    case wifi
    case wwan
    case noConnection
}


enum NetworkMonitorError: Error {
    case notStarted
    case unavailable
}


final class NetworkMonitor {
    
    // MARK: -
    // MARK: Properties
    
    private let monitor: Reachability?
    
    let status: SignalProducer<NetworkStatus, NetworkMonitorError>
    
    
    // MARK: -
    // MARK: Initialization
    
    init() {
        let monitor = Reachability()
        
        self.monitor = monitor
        self.status = SignalProducer { observer, disposable in
            guard let monitor = monitor else {
                observer.send(error: .unavailable)
                return
            }
            
            monitor.whenReachable = { reachability in
                if reachability.isReachableViaWiFi {
                    observer.send(value: .wifi)
                }
                
                if reachability.isReachableViaWWAN {
                    observer.send(value: .wwan)
                }
            }
            
            monitor.whenUnreachable = { _ in
                observer.send(value: .noConnection)
            }
            
            do {
               try monitor.startNotifier()
            } catch {
                observer.send(error: .notStarted)
            }
            
        }
    }
    
}

To demo, you can use this:

let monitor = NetworkMonitor()

monitor.status
    .on(
        failed: { print("error: \($0)") },
        value:  { print("value: \($0)") }
    )
    .start()