How to update user metadata from iOS SDK?

When I try to use the management API from the iOS SDK to update the user’s metadata,

[manageAPI patchUserWithIdentifier:identity.identifier userMetadata:[self fieldsToDictionary] callback:^(NSError * _Nullable error, NSDictionary * _Nullable data)

It keeps giving me an HTTP error.

Error: Failed with unknown error “errorCode”: Bearer, “message”: Bad HTTP authentication header format, “statusCode”: 400, “error”: Bad Request]

Any ideas why I’m getting this error?

OK. I’m very confused on how to update metadata from Auth0 SDK for iOS. My user is logged in and authenticated. I don’t understand why I can’t call the manageAPI to patch the user. Is there something I’m missing?
@prashant