I am trying to learn the Contacts Framework and would very much appreciate someone explaining the following:
What a container is; and
What a container id is and how they work.
Specifically, in the following code I understand that the constant predicate is used to filter the individual contacts that are fetched and stored in array contacts but I do not understand how / why line 42 and 44 work to filter (i.e. include) all contacts.
I tried searching the web, YouTube, etc. and all the examples / explanations were far too complicated.