First of all there's PaintCode - the name is pretty much self explanitory. You importort a PSD file and it generates code in Swift or Objective-C to paint the element using Core Graphics.
You can customize a great deal of the element and it's easy to add your own animations on top when you get it into Xcode.
Then there's xScope - a complete tool that let's you meassure, inspect, align your layouts.
Sip - a rich color picker with support for lots of languages. Easily get a UIColor instance from any pixel on your screen. Super easy.
And last, Tokens. Get those App Store promo codes working for you and see if people redeem them, add a campaign where people get codes on a first-come first-served basis.