I would highly recommend going native for building games. With HTML5 you won't get the performance you do from a native app primarily because OpenGL is hardware

I would highly recommend going native for building games. With HTML5 you won't get the performance you do from a native app primarily because OpenGL is hardware accelerated and performs very well on iDevices. Plus JavaScript executes fairly slowly in UIWebViews. If you spend a lot of time you can improve the performance, but it will still be much worse than native if you're shooting for a frame rate >30fps and plan to have many elements on the screen. Shameless self plug: If you're looking to build an iPhone game check out our website (https://www.makegameswith.us https://www.makegameswith.us), you'll learn how to build Angry Birds in no time then get started making your own game!