iOS实时监控网络状态的改变

typedef enum : NSInteger {  NotReachable = 0, //无连接  ReachableViaWiFi, //使用3G/GPRS网络  ReachableViaWWAN //使用WiFi网络} NetworkStatus;

// AppDelegate.m@interface AppDelegate ()@property (nonatomic, strong) Reachability *reachability;@end// 程序启动器，启动网络监视- (void)applicationDidFinishLaunching:(UIApplication *)application {  // 设置网络检测的站点    NSString *remoteHostName = @"www.apple.com";  self.reachability = [Reachability reachabilityWithHostName:remoteHostName];  // 设置网络状态变化时的通知函数  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:)                       name:@"kNetworkReachabilityChangedNotification" object:nil];  [self updateStatus];}- (void)reachabilityStatusChange:(NSNotification *)notification{  Reachability* curReach = [notification object];  NSParameterAssert([curReach isKindOfClass:[Reachability class]]);  [self updateInterfaceWithReachability:curReach];}- (void)updateInterfaceWithReachability:(Reachability *)reachability{  if (reachability == _reachability)  {    NetworkStatus netStatus = [reachability currentReachabilityStatus];    switch (netStatus)    {      case NotReachable:   {        NSLog(@"没有网络！");        break;      }      case ReachableViaWWAN: {        NSLog(@"4G/3G");        break;      }      case ReachableViaWiFi: {        NSLog(@"WiFi");        break;      }    }  }}- (void)dealloc{   [_reachability stopNotifier];  [[NSNotificationCenter defaultCenter] removeObserver:self name:kReachabilityChangedNotification object:nil];} 

//使用AFN框架来检测网络状态的改变-(void)AFNReachability{  //1.创建网络监听管理者  AFNetworkReachabilityManager *manager = [AFNetworkReachabilityManager sharedManager];  //2.监听网络状态的改变  /*   AFNetworkReachabilityStatusUnknown     = 未知   AFNetworkReachabilityStatusNotReachable   = 没有网络   AFNetworkReachabilityStatusReachableViaWWAN = 3G   AFNetworkReachabilityStatusReachableViaWiFi = WIFI   */  [manager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {    switch (status) {      case AFNetworkReachabilityStatusUnknown:        NSLog(@"未知");        break;      case AFNetworkReachabilityStatusNotReachable:        NSLog(@"没有网络");        break;      case AFNetworkReachabilityStatusReachableViaWWAN:        NSLog(@"3G");        break;      case AFNetworkReachabilityStatusReachableViaWiFi:        NSLog(@"WIFI");        break;      default:        break;    }  }];  //3.开始监听  [manager startMonitoring];}