I checked out Tangram from App Store. How can I make this bevel effect on different shapes? What technology do I need create such a layout?
Do I need OpenGL ES or cocos2D maybe Quartz2D?
Actually I've documented the development process of tangram!, find it here: http://gotoandplay.freeblog.hu/categories/compactTangram/
At that time there was no option to render OpenGL polygons with anti-aliasing, so I made a demanding workaround to achieve the result (I wanted to add bump effect too, but later on I skipped). The point is in this post: http://gotoandplay.freeblog.hu/archives/2010/02/04/compactTangram_074_-_organizing_textures_performance_preservingincreasing_plan/ Funny.
Since than, you can easily render with anti-alias, and retina also a solution for that pain, so some polygon mesh, some shader for specular stuff, and there you go, or go with Cocos2D, as you mentioned, it has growing 3D support.