Sketch Talk - A community for Sketch users of all skill levels
Xcode - Xcode is Apple’s powerful integrated development environment for creating great apps for Mac, iPhone, and iPad. Xcode 4 includes the Xcode IDE, instruments, iOS Simulator, and the latest Mac OS X and iOS SDKs.
SketchCasts - A weekly screencast, all about how to use Sketch
Swift Playgrounds - Learn serious code on your iPad in a seriously fun way
GoRails - Ruby on Rails screencasts for Web Developers
Angle 2 Mockups - A giant Sketch Library for creating app presentations