Why in Xcode 6 doesn't work Assistant Preview?

Question

Sometimes in Xcode 6 Assistant Editor -> Preview stops working.

Showing just "No selection" even if no errors and Storyboard is ok.

Why does this happen?

Answer 1

The reason is "?" (questionmark) in Project's name (maybe there is a bug with other symbols – didn't check it).

You can try to rename Project or just create new one with name without "?" in it.