iOS Design Kit - The newest library of native iOS templates
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
iOS Design Course - The Complete iOS Design Course with Sketch from Bitfountain
Sketch - Professional digital design for Mac.
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.
Affinity Designer - Professional creative software, exclusively for Mac.