AFNetWorking monitors network status

 AFNetworkReachabilityManager *manager = [AFNetworkReachabilityManager sharedManager];
    [manager startMonitoring];
    [manager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {         switch (status) {             case AFNetworkReachabilityStatusUnknown:                 NSLog(@"未识别的网络");                 break;             case AFNetworkReachabilityStatusNotReachable:{                 UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Prompt" message:@"The current network is unavailable, please check the network settings" preferredStyle:UIAlertControllerStyleAlert]; UIAlertAction *action = [UIAlertAction actionWithTitle:@"OK"                 style:UIAlertActionStyleDefault handler:nil];




                



                [alert addAction:action];
                [[UIApplication sharedApplication].keyWindow.rootViewController presentViewController:alert animated:YES completion:nil];
            }
               
                break;
                
            case AFNetworkReachabilityStatusReachableViaWWAN:
                NSLog(@"2G,3G,4G...的网络");
                break;
                
            case AFNetworkReachabilityStatusReachableViaWiFi:
                NSLog(@"wifi的网络");
                break;
            default:
                break;
        }
    }];