The Contacts view on iOS consists of a Quick search filter field, the contact list itself and an annotated scrolllbar that lets people jump directly to specific letters.
To me the annotated scrollbar is redundant. If I enter a letter in the search field the list is filtered and only show the contacts that contains that letter which is the same as if I click on the letter in the annotated scrollbar. To me the search field is superior when I want to find a specific contact.
What are the use cases for using both an search field and an annotated scrollbar?