NSTokenField is particularly tricky to use with Core Data bindings. I wanted to model a to-many relationship between an object (specifically Client, Project, etc.) and multiple Tags. The user would select e.g. a client from a table view, and in the inspector panel a token field would represent the assigned tags, which the user can edit. It’s a typical master-detail configuration. Tags that already exist are autocompleted; non-existent tags are created once the focus leaves the field.