网络监听

1. AFNetworking自带

-(void)startnetwork
{
   AFNetworkReachabilityManager *manager = [AFNetworkReachabilityManager sharedManager];
   [manager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
       // 当网络状态改变时调用
       switch (status) {
           case AFNetworkReachabilityStatusUnknown:
               [self showHudTipStr:@"未知网络"];
               break;
           case AFNetworkReachabilityStatusNotReachable:
           {
               [self showHudTipStr:@"无网络连接"];
           }
               break;
           case AFNetworkReachabilityStatusReachableViaWWAN:
               [self showHudTipStr:@"已连接2G/3G/4G"];
               [self autoUpdataToServer];
               break;
           case AFNetworkReachabilityStatusReachableViaWiFi:
               [self showHudTipStr:@"已连接WIFI"];
               [self autoUpdataToServer];
               break;
       }
   }];
   //开始监控
   [manager startMonitoring];
}

2. Reachability

//开启网络状况的监听
   [[NSNotificationCenter defaultCenter] addObserver:self
                                            selector:@selector(reachabilityChanged:)
                                                name: kReachabilityChangedNotification
                                              object: nil];
   hostReach =[Reachability reachabilityWithHostName:@"wap.baidu.com"];//可以以多种形式初始化
   [hostReach startNotifier]; //开始监听,会启动一个run loop

// 1.检测wifi状态
   Reachability *wifi = [Reachability reachabilityForLocalWiFi];
   // 2.检测手机是否能上网络(WIFI\3G\2.5G)
   Reachability *conn = [Reachability reachabilityForInternetConnection];
   // 3.判断网络状态
   if ([wifi currentReachabilityStatus] != NotReachable) { // 有wifi
       return YES;
   } else if ([conn currentReachabilityStatus] != NotReachable) { // 没有使用wifi, 使用手机自带网络进行上网
       return YES;
   } else { // 没有网络
       return NO;
   }