UDK is going to get iOS support in its next release 
With Infinity Blade becoming the fastest grossing iOS application ever, there is no better time to unleash the power of UDK on the iPhone/iPad for your game 
Epic co-founder Mark Rein wrote:
Apple’s App Store is the most vibrant market for mobile gaming,” “If you’re going to make a game for a mobile device, and you want to make the most money, you’re nuts not to make it for iOS.