在 Windows Phone 8.1 中生成 Chanal Uri 时发生“System.NullReferenceException”

Question

每当我尝试在 windows phone 7 和 windows phone 8 中创建推送通知时，我的代码都可以正常工作，但每当我尝试在 windows phone 8.1 上构建相同的代码时，它都会显示“System.NullReferenceException”在生成 Chanal Uri 时发生在 Windows Phone 8.1 中。

代码如下：

            String channelUri="XYZ";
            HttpNotificationChannel myPushChannel = HttpNotificationChannel.Find(channelUri);
            if (null == myPushChannel)
            {

                    myPushChannel = new HttpNotificationChannel(channelUri);
                    myPushChannel.Open();
                    myPushChannel.ShellToastNotificationReceived += new EventHandler<NotificationEventArgs>(myPushChannel_ShellToastNotificationReceived);
                    myPushChannel.ChannelUriUpdated += new EventHandler<NotificationChannelUriEventArgs>(myPushChannel_ChannelUriUpdated);
                    myPushChannel.ErrorOccurred += new EventHandler<NotificationChannelErrorEventArgs>(myPushChannel_ErrorOccurred);
                    myPushChannel.HttpNotificationReceived += new EventHandler<HttpNotificationEventArgs>(myPushChannel_HttpNotificationReceived);
                    myPushChannel.BindToShellTile();
                    myPushChannel.BindToShellToast();
                    uri = myPushChannel.ChannelUri;
            }
            else
            {

                if (myPushChannel != null)
                {
                    myPushChannel.ShellToastNotificationReceived += new EventHandler<NotificationEventArgs>(myPushChannel_ShellToastNotificationReceived);
                    myPushChannel.ChannelUriUpdated += new EventHandler<NotificationChannelUriEventArgs>(myPushChannel_ChannelUriUpdated);
                    myPushChannel.ErrorOccurred += new EventHandler<NotificationChannelErrorEventArgs>(myPushChannel_ErrorOccurred);
                    myPushChannel.HttpNotificationReceived += new EventHandler<HttpNotificationEventArgs>(myPushChannel_HttpNotificationReceived);
                    uri = myPushChannel.ChannelUri;
                    if (!myPushChannel.IsShellToastBound)
                        myPushChannel.BindToShellToast();
                        if (!myPushChannel.IsShellTileBound)
                        myPushChannel.BindToShellTile();
                }

            }
        }

在 windows phone 7/8 上一切正常，但在 windows phone 8.1 上却不行。

Answer 1

如果我们谈论的是 WP8.1 通用应用程序，而不是 silverlight，您应该使用下面的行来获取 PushNotificationChannel：

PushNotificationChannel channel = await PushNotificationChannelManager.CreatePushNotificationChannelForApplicationAsync();