objective c - UITableView: how to magnify selected section index letter on the right side section index? -

objective c - UITableView: how to magnify selected section index letter on the right side section index? -

i cannot remember exactly, remember 1 app time ago section letters (a, b, c, d...) seen in section index (at right side), magnified, user tapped , scrolled on index. check link bluish letters seen @ right side. example, if user taps on letter e in section index letter magnified , becomes larger others. 2 other letters (d , f) @ side magnified little bit less. user can see section index letter holding. i'm searching , trying find how enable feature (section index height or smth), unable find it. recap that?

here's sketch describes idea:

i dont think can enable. looks custom scrollview me.

but luckily have starred on github sometime ago guess similar have requested

https://github.com/matthewfx/mjnindexview

objective-c uitableview sections