title: iOS transitions become instantaneous
body: <p>I'm developing a basic iOS app that doesn't use any fancy animations except for the built in transitions between views. After testing the app on both the simulator and an iPhone 4S for a while, the animations suddenly become instantaneous. For example, clicking the back button makes the previous view appear instantly instead of sliding back in. </p>
  
  <p>I don't get any errors, and I don't call setAnimationsEnabled at any point. The app remains fully functional except for the lack of animations.</p>
  
  <p><strong>EDIT:</strong> Occasionally, the tab bar items also disappear. This doesn't always happen, but the disappearing only happens when the animations stop working so I'm guessing they're somehow related.</p>
  
  <p>Any ideas what the problem might be?</p>