iOS Design Kit - The newest library of native iOS templates
WuHoo - DIY scene generator and mockups with customizable graphics.
iOS Design Course - The Complete iOS Design Course with Sketch from Bitfountain
NinjaMock - NinjaMock is the faster, better and funnier way of making mockups
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.
Mockup Generator by Pixeltrue - Create beautiful product mockups in just a few clicks