iOS 实时监测网络状态（通过Reachability）

在AppDelegate.m中

 @property (nonatomic, strong) Reachability *reach;

 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

     // 监测网络情况
     [[NSNotificationCenter defaultCenter] addObserver:self
                                              selector:@selector(reachabilityChanged:)
                                                  name: kReachabilityChangedNotification
                                                object: nil];
     Reachability *reach = [Reachability reachabilityWithHostName:@"www.apple.com"];
     [reach startNotifier];
     self.reach = reach;
 }

通知触发执行的方法

 #pragma mark - 网络状态变化通知
 - (void)reachabilityChanged:(NSNotification*)note {

     Reachability* curReach = [note object];
     NSParameterAssert([curReach isKindOfClass: [Reachability class]]);
     NetworkStatus status = [curReach currentReachabilityStatus];

     /*
      NotReachable = 0, 无网络连接
      ReachableViaWiFi, Wifi
      ReachableViaWWAN 2G/3G/4G/5G
      */
     if (status == NotReachable) {

        // 没有网络的更多操作
 // 实现类似接到电话效果   self.window.frame = CGRectMake(0, 40, __width, __height-40);

     } else if (status == ReachableViaWiFi) {
         NSLog(@"Wifi");
     } else {
         NSLog(@"3G/4G/5G");
     }
 }

 - (void)dealloc {
     [_reach stopNotifier];
     [[NSNotificationCenter defaultCenter] removeObserver:self];
 }

完毕，亲测可用