Intriguing tool for tweaking your iOS UIs live on a device, including overlaying design comps.

http://mireus.com/xrayeditor/

Developers prefer Apple's iOS Maps SDK over Google Maps

http://appleinsider.com/articles/13/03/18/developers-prefer-apples-ios-maps-sdk-over-google-maps

350+ Free Retina Display Vector Icons

http://graphicdesignjunction.com/2013/03/retina-display-vector-icons/

Building with Blocks

http://skookum.com/blog/building-with-blocks/

Optimization Responsively Retrofitting An Existing Site With RWD Retrofit

http://mobile.smashingmagazine.com/2013/03/18/retrofit-a-website-to-be-responsive-with-rwd-retrofit/

10 Things Web Designers Need To Know About App Design

http://www.creativebloq.com/app-design/web-designers-need-know-3132155