How to implement ios contact list header style header?

I want to implement a list which is like ios contact list with letter header stucks when scrolls top.

I have a list:

$scope.lst = [{type:header,value:A} {bla:1,bla:2...},{bla:3,bla:4...}......{type:header,value:B},{bla:3,bla:4...}....];

binding from list:

   .item   (if type <> header)
   .header (if type = header)

Header must be stuck on top when scroll up.

Sorry for my poor english.