对于IOS 8，IOS远程通知无法在后台运行

Question

我一直在使用Xamarin.IOS，最近我遇到了在Iphone / Ipad处于后台时尝试接收远程通知负载的问题。 IOS 7设备似乎在后台或前台工作。但是，对于IOS 8设备，仅在触摸警报横幅时才会调用DidReceiveRemoteNotification。我需要能够在未触及警报横幅且应用程序处于后台时获取有效负载。为什么远程通知在IOS 7的后台工作，而IOS 8则不工作。我可能做错了什么？

if (UIDevice.CurrentDevice.SystemVersion [0] >= '8')
    {
        UIUserNotificationType types = UIUserNotificationType.Badge | UIUserNotificationType.Sound | UIUserNotificationType.Alert;
        UIUserNotificationSettings settings = UIUserNotificationSettings.GetSettingsForTypes (types, null);
        UIApplication.SharedApplication.RegisterUserNotificationSettings (settings);
    }
    else
    {
        UIRemoteNotificationType notificationTypes = UIRemoteNotificationType.Alert | UIRemoteNotificationType.Badge |                                                      
        UIRemoteNotificationType.Sound;
        UIApplication.SharedApplication.RegisterForRemoteNotificationTypes (notificationTypes);
    } 

Answer 1

如果版本是iOS 8或更高版本，则需要调用RegisterForRemoteNotifications方法：

if (UIDevice.CurrentDevice.SystemVersion [0] >= '8')
{
    UIUserNotificationType types = UIUserNotificationType.Badge | UIUserNotificationType.Sound | UIUserNotificationType.Alert;
    UIUserNotificationSettings settings = UIUserNotificationSettings.GetSettingsForTypes (types, null);
    UIApplication.SharedApplication.RegisterUserNotificationSettings (settings);
    UIApplication.SharedApplication.RegisterForRemoteNotifications();
}