Xamarin Forms iOS - Saving a user tag in Azure Notification Hubs works in AppDelegate but not in a service - xamarin.forms

Question

I'm currently trying to get push notifications working for my mobile app using Azure Notification Hubs. Android is working fine and the initial iOS set up in AppDelegate works ok with a sample tag.
public override void RegisteredForRemoteNotifications(UIApplication application, NSData deviceToken)
{
if (deviceToken == null)
{
return;
}
SBNotificationHub hub = new SBNotificationHub(CommonConstants.LISTEN_CONNECTION_STRING, CommonConstants.NOTIFICATION_HUB_NAME);
// update registration with Azure Notification Hub
hub.UnregisterAll(deviceToken, async (error) =>
{
if (error != null)
{
System.Diagnostics.Debug.WriteLine($"Unable to call unregister {error}");
return;
}
string[] tags = new[] { "iostestpush" };
NSSet userTags = new NSSet(tags);
hub.RegisterNative(deviceToken, userTags, (error) =>
{
if (error != null)
{
System.Diagnostics.Debug.WriteLine($"Unable to call register {error}");
return;
}
});
var templateExpiration = DateTime.Now.AddDays(120).ToString(System.Globalization.CultureInfo.CreateSpecificCulture("en-US"));
hub.RegisterTemplate(deviceToken, "defaultTemplate", CommonConstants.APN_TEMPLATE_BODY, templateExpiration, userTags, (errorCallback) =>
{
if (errorCallback != null)
{
System.Diagnostics.Debug.WriteLine($"RegisterTemplateAsync error: {errorCallback}");
}
});
});
}
The issue I'm having is I need to register the UserId after a successful login. So I set up a service with the above code, saved the token to the device as string so it can be retrieved in the service and turned back into an NSData token
NSData deviceToken = new NSData(token, NSDataBase64DecodingOptions.None);
After a successful login I send the token string and the tag array to my service.
string[] userTag = new[] { loginResponse.UserId.ToString() };
await this._azureReg.SendRegistrationToServer(deviceToken, userTag);
Which, other than turning the token back into NSData and the user tag into an NSSet, is the same as above other than the name change. But Azure is claiming there is no registration even though my output shows
Registered for push notifications with token: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I thought it was the string conversion back and forth, so tested that in the AppDelegate and it worked fine.
So, I'm at a loss at how to register the UserId after a successful login and why it works in one place but not the other.
I hope that's clear and thanks for any advice in advance.

Answer 1

You probably ran into the same bug as me and several others.
Basically SBNotificationHub method overloads like UnregisterAll and RegisterTemplate with the callback signature do not work when you use them off the main thread, using the libraries to date. I was also using a Service for the same purpose (to handle push across platforms with different tags, especially for user id) but my implementation involved switching off the main thread for this.
The bug we logged and is now being addressed is here: https://github.com/Azure/azure-notificationhubs-ios/issues/95
The solution, for now, is to ditch SBNotificationHub completely. The Xamarin / Azure documentation is out of date, and SBNOtificationHub is legacy code. The recommended library is MSNotificationHub. https://github.com/azure/azure-notificationhubs-xamarin
As workarounds you can use the SBNotificationHub method overloads that do not involve callbacks (they return an error message instead) or the workaround in the 95 issue above.