如果用户连接到没有活动互联网连接的wifi网络，如何检测场景？
可以通过互联网连接检测wifi连接。 我从这里下载了样品。
https://github.com/xamarin/ios-samples/tree/master/ReachabilitySample
它在Xamarin编码，但我也对swift或objective c中的解决方案感兴趣。
// Reachability.cs
using System;
using System.Net;
using SystemConfiguration;
using CoreFoundation;
namespace Reachability {
public enum NetworkStatus {
NotReachable,
ReachableViaCarrierDataNetwork,
ReachableViaWiFiNetwork
}
public static class Reachability {
public static string HostName = "www.google.com";
public 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
|| (flags & NetworkReachabilityFlags.IsWWAN) != 0;
return isReachable && noConnectionRequired;
}
// Is the host reachable with the current network configuration
public static bool IsHostReachable (string host)
{
if (string.IsNullOrEmpty (host))
return false;
using (var r = new NetworkReachability (host)) {
NetworkReachabilityFlags flags;
if (r.TryGetFlags (out flags))
return IsReachableWithoutRequiringConnection (flags);
}
return false;
}
//
// Raised every time there is an interesting reachable event,
// we do not even pass the info as to what changed, and
// we lump all three status we probe into one
//
public static event EventHandler ReachabilityChanged;
static void OnChange (NetworkReachabilityFlags flags)
{
ReachabilityChanged?.Invoke (null, EventArgs.Empty);
}
//
// Returns true if it is possible to reach the AdHoc WiFi network
// and optionally provides extra network reachability flags as the
// out parameter
//
static NetworkReachability adHocWiFiNetworkReachability;
public static bool IsAdHocWiFiNetworkAvailable (out NetworkReachabilityFlags flags)
{
if (adHocWiFiNetworkReachability == null) {
var ipAddress = new IPAddress (new byte[] { 169, 254, 0, 0 });
adHocWiFiNetworkReachability = new NetworkReachability (ipAddress.MapToIPv6 ());
adHocWiFiNetworkReachability.SetNotification (OnChange);
adHocWiFiNetworkReachability.Schedule (CFRunLoop.Current, CFRunLoop.ModeDefault);
}
return adHocWiFiNetworkReachability.TryGetFlags (out flags) && IsReachableWithoutRequiringConnection (flags);
}
static NetworkReachability defaultRouteReachability;
static bool IsNetworkAvailable (out NetworkReachabilityFlags flags)
{
if (defaultRouteReachability == null) {
var ipAddress = new IPAddress (0);
defaultRouteReachability = new NetworkReachability (ipAddress.MapToIPv6 ());
defaultRouteReachability.SetNotification (OnChange);
defaultRouteReachability.Schedule (CFRunLoop.Current, CFRunLoop.ModeDefault);
}
return defaultRouteReachability.TryGetFlags (out flags) && IsReachableWithoutRequiringConnection (flags);
}
static NetworkReachability remoteHostReachability;
public static NetworkStatus RemoteHostStatus ()
{
NetworkReachabilityFlags flags;
bool reachable;
if (remoteHostReachability == null) {
remoteHostReachability = new NetworkReachability (HostName);
// Need to probe before we queue, or we wont get any meaningful values
// this only happens when you create NetworkReachability from a hostname
reachable = remoteHostReachability.TryGetFlags (out flags);
remoteHostReachability.SetNotification (OnChange);
remoteHostReachability.Schedule (CFRunLoop.Current, CFRunLoop.ModeDefault);
} else {
reachable = remoteHostReachability.TryGetFlags (out flags);
}
if (!reachable)
return NetworkStatus.NotReachable;
if (!IsReachableWithoutRequiringConnection (flags))
return NetworkStatus.NotReachable;
return (flags & NetworkReachabilityFlags.IsWWAN) != 0 ?
NetworkStatus.ReachableViaCarrierDataNetwork : NetworkStatus.ReachableViaWiFiNetwork;
}
public static NetworkStatus InternetConnectionStatus ()
{
NetworkReachabilityFlags flags;
bool defaultNetworkAvailable = IsNetworkAvailable (out flags);
if (defaultNetworkAvailable && ((flags & NetworkReachabilityFlags.IsDirect) != 0))
return NetworkStatus.NotReachable;
if ((flags & NetworkReachabilityFlags.IsWWAN) != 0)
return NetworkStatus.ReachableViaCarrierDataNetwork;
if (flags == 0)
return NetworkStatus.NotReachable;
return NetworkStatus.ReachableViaWiFiNetwork;
}
public static NetworkStatus LocalWifiConnectionStatus ()
{
NetworkReachabilityFlags flags;
if (IsAdHocWiFiNetworkAvailable (out flags))
if ((flags & NetworkReachabilityFlags.IsDirect) != 0)
return NetworkStatus.ReachableViaWiFiNetwork;
return NetworkStatus.NotReachable;
}
}
}
// MainViewController.cs
using System;
using Foundation;
using UIKit;
namespace Reachability {
public partial class MainViewController : UITableViewController {
const string ReachabilityTableCellIdentifier = "ReachabilityTableCell";
UIImage imageCarrier, imageWiFi, imageStop;
NetworkStatus remoteHostStatus, internetStatus, localWifiStatus;
public MainViewController (IntPtr handle) : base (handle)
{
}
public override void ViewDidLoad ()
{
base.ViewDidLoad ();
UpdateStatus (null, null);
Reachability.ReachabilityChanged += UpdateStatus;
imageCarrier = UIImage.FromFile ("WWAN5.png");
imageWiFi = UIImage.FromFile ("Airport.png");
imageStop = UIImage.FromFile ("stop-32.png");
TableView.AutoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight;
TableView.RowHeight = 44f;
TableView.SeparatorStyle = UITableViewCellSeparatorStyle.None;
TableView.SectionHeaderHeight = 28f;
TableView.ScrollEnabled = false;
}
public override NSIndexPath WillSelectRow (UITableView tableView, NSIndexPath indexPath)
{
return null;
}
public override nint RowsInSection (UITableView tableView, nint section)
{
return 1;
}
public override nint NumberOfSections (UITableView tableView)
{
return 3;
}
public override string TitleForHeader (UITableView tableView, nint section)
{
switch (section) {
case 0:
return Reachability.HostName;
case 1:
return "Access to internet hosts";
case 2:
return "Access to Local Bonjour Hosts";
default:
return "Unknown";
}
}
public override UITableViewCell GetCell (UITableView tableView, NSIndexPath indexPath)
{
var cell = tableView.DequeueReusableCell (ReachabilityTableCellIdentifier);
if (cell == null) {
cell = new UITableViewCell (UITableViewCellStyle.Default, ReachabilityTableCellIdentifier);
var label = cell.TextLabel;
label.Font = UIFont.SystemFontOfSize (12f);
label.TextColor = UIColor.DarkGray;
label.TextAlignment = UITextAlignment.Left;
}
string text = string.Empty;
UIImage image = null;
switch (indexPath.Section) {
case 0:
switch (remoteHostStatus) {
case NetworkStatus.NotReachable:
text = "Cannot connect to remote host";
image = imageStop;
break;
case NetworkStatus.ReachableViaCarrierDataNetwork:
text = "Reachable via data carrier network";
image = imageCarrier;
break;
case NetworkStatus.ReachableViaWiFiNetwork:
text = "Reachable via WiFi network";
image = imageWiFi;
break;
}
break;
case 1:
switch (internetStatus) {
case NetworkStatus.NotReachable:
text = "Access not available";
image = imageStop;
break;
case NetworkStatus.ReachableViaCarrierDataNetwork:
text = "Available via data carrier network";
image = imageCarrier;
break;
case NetworkStatus.ReachableViaWiFiNetwork:
text = "Available via WiFi network";
image = imageWiFi;
break;
}
break;
case 2:
switch (localWifiStatus) {
case NetworkStatus.NotReachable:
text = "Access not available";
image = imageStop;
break;
case NetworkStatus.ReachableViaWiFiNetwork:
text = "Available via WiFi network";
image = imageWiFi;
break;
}
break;
}
cell.TextLabel.Text = text;
cell.ImageView.Image = image;
return cell;
}
void UpdateStatus (object sender, EventArgs e)
{
remoteHostStatus = Reachability.RemoteHostStatus ();
internetStatus = Reachability.InternetConnectionStatus ();
localWifiStatus = Reachability.LocalWifiConnectionStatus ();
TableView.ReloadData ();
}
}
}