AFNetworking はネットワークの状態を監視します

 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" メッセージ:@"現在のネットワークを利用できません。ネットワーク設定を確認してください" preferredStyle:UIAlertControllerStyleAlert]; UIAlertAction *action = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:                 nil ];




                



                [アラート addAction:アクション];
                [[UIApplication sharedApplication].keyWindow.rootViewController presentViewController:alert animation:YES 完了:nil];
            }
               
                ブレーク;
                
            case AFNetworkReachabilityStatusReachableViaWWAN:
                NSLog(@"2G,3G,4G...的网络");
                壊す;
                
            case AFNetworkReachabilityStatusReachableViaWiFi:
                NSLog(@"wifi的网络");
                壊す;
            デフォルト:
                ブレーク;
        }
    }];