#import "Reachability.h"      @interface JRViewController ()<UIActionSheetDelegate>  @property(nonatomic,strong)  Reachability * reach;  @end      @implementation JRViewController      - (void)viewDidLoad {      [super viewDidLoad];          //监听Reachability.h————————————————————————————————————————————————————————————————            //      [self monitorNetState:nil];            // 开启通知监控，实时等待      [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(monitorNetState:) name:kReachabilityChangedNotification object:nil];//object是指监听谁发出的通知，在这里可以写self.reach,也可以写nil      [self.reach startNotifier];//一定要写开始监控        }        //**********************************************  //reachability监听————————————————————————————————————————————————————————————————  - (void) monitorNetState:(NSNotification *)noti  {      NSLog(@"%@", noti);      if(self.reach==nil)//      {          self.reach=[Reachability reachabilityForInternetConnection];//不是单例                              //他还有两个子类  //        ReachableViaWiFi;  //        ReachableViaWWAN;                    }            if(self.reach.currentReachabilityStatus!=NotReachable)      {                    if (self.reach.currentReachabilityStatus==ReachableViaWiFi)          {              NSLog(@"wifi");          }          else          {              NSLog(@"3g/2g");          }      }      else      {          NSLog(@"没有网");      }  }      //移除监听  -(void)dealloc{      //reachability需要自己停止      [self.reach stopNotifier];            [[NSNotificationCenter defaultCenter] removeObserver:self];  }      @end