How To Check Network Reachability With Xamarin.iOS on iOS 8

Therefore it's convenient to check the availability of an established internet connection, so you can show some warnings or instructions if the device isn't connected.

Thankfully there's a simple solution around for years, see the ReachabilitySample on GitHub. It's using some handy features that are baked-in in iOS. So it's not necessary to ping a server every x seconds, instead the operating system sends notifications about changes regarding the network connection you can subscribe to.

The bad thing is: That doesn't seem to work properly on iOS 8.3 anymore, so I had to do some investigation. At the end of it most of the class was gone, but what was left, is now working.

I won't do a pull-request because I deleted most of the public stuff and instead went for a much simpler API, that only tells if the device is connected or not. But maybe it's useful for someone else, so here it is:

using System;
using System.Net;
using SystemConfiguration;
using CoreFoundation;

public enum NetworkStatus
{
    NotReachable,
    ReachableViaCarrierDataNetwork,
    ReachableViaWiFiNetwork
}

public static class Reachability
{
    private static NetworkReachability _defaultRouteReachability;

    public static event EventHandler ReachabilityChanged;

    public static bool IsNetworkAvailable()
    {
        if (_defaultRouteReachability == null)
        {
            _defaultRouteReachability = new NetworkReachability(new IPAddress(0));
            _defaultRouteReachability.SetNotification(OnChange);
            _defaultRouteReachability.Schedule(CFRunLoop.Current, CFRunLoop.ModeDefault);
        }

        NetworkReachabilityFlags flags;

        return _defaultRouteReachability.TryGetFlags(out flags) &&
            IsReachableWithoutRequiringConnection(flags);
    }

    private static bool IsReachableWithoutRequiringConnection(NetworkReachabilityFlags flags)
    {
        // Is it reachable with the current network configuration?
        bool isReachable = (flags & NetworkReachabilityFlags.Reachable) != 0;

        // Do we need a connection to reach it?
        bool noConnectionRequired = (flags & NetworkReachabilityFlags.ConnectionRequired) == 0;

        // Since the network stack will automatically try to get the WAN up,
        // probe that
        if ((flags & NetworkReachabilityFlags.IsWWAN) != 0)
            noConnectionRequired = true;

        return isReachable && noConnectionRequired;
    }

    private static void OnChange(NetworkReachabilityFlags flags)
    {
        var h = ReachabilityChanged;
        if (h != null)
            h(null, EventArgs.Empty);
    }
}