Okay, I've been having this issue since I upgraded to iOS8 with my iPhone 5 and now this issue has carried over my iPhone 6.... Basically the touchscreen stops working, can't zoom or tap, once I press the home screen then everything starts working again, but if I go back to the app it doesn't respond, so the only way I can fix this is to power off and on the iPhone again and everything seems to work fine. This happens mainly when I playing games such Clash of Clans or Angry Birds Transformers...these are the main games I really play... Anyone running into this problem or is it just me? I've read few suggestions by resetting your settings on your iPhone but that did not fix this issue for me at all. The only other thing I can think of doing is doing a full wipe of my iPhone.