Hi Jarno,
The u object is private and should not be accessed. It's used as a shorthand inside the send function of each tag to refer to that tag's configuration data, such as mappings. The b object is the only one you should ever need to access.
Cheers,
Craig.
Check out our new Swift integration library for iOS, macOS, tvOS and watchOS: https://github.com/Tealium/tealium-swift with updated
documentation https://community.tealiumiq.com/t5/Swift/tkb-p/swift.