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I have a bare-bones iPad app that experiences odd pixel flickering along the very top of the screen when the iPad's orientation changes. The view my app is displaying is also bare-bones; it comes from the "View-Based Application" template in Xcode 4.

I'm surprised to see flickering along the top when I rotate the iPad's screen; even if my view is empty (no controls), I still see the flickering.

Is it possible that it's happening because I'm running a debug build? I haven't tried a release build yet; I wanted to see if this is specific to debug mode, or if there is something else I haven't yet taken into consideration.

Edit: just to clarify, I see the flickering while running my app on a first gen iPad, not under the iOS Simulator. The app is built with Xcode 4.1, running under Lion. No other apps on my iPad exhibit the flickering I'm seeing with my app during orientation changes.

Rob
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  • Just to clarify, you're seeing this with the default template? Are you on Lion or SL? There are some graphics glitches in Lion (rare, but happens more often on older hardware—I have them on an iMac8,1); if it's with the default template, I'm tempted to think it might be a hardware issue on your part. Try rebooting your system (if it is the graphics issue at fault)? – FeifanZ Aug 04 '11 at 01:35
  • Lion, but it's actually running on a first gen iPad - I don't see the flickering under the simulator. – Rob Aug 04 '11 at 01:55
  • Okay, what about the other templates? Which compiler are you using, BTW? Try putting an autoresizing view into your app—does that flicker when you rotate? – FeifanZ Aug 04 '11 at 10:49
  • I'll try some of the other templates, and yes, I believe the view is autoresizing. That being said, I've seen many iPad apps with autoresizing views; I'm just surprised to see any sort of visual artifacts during rotation. Seems pretty surprising. – Rob Aug 04 '11 at 15:58
  • Compiler is whatever comes default with Xcode 4.1 - most likely not LLVM, though. – Rob Aug 04 '11 at 15:59
  • No, I meant try adding a new view (label, or even just a plain UIView), set some autoresizing masks, and see if that new view flickers. Also, what else is running on your iPad at the moment? Unlikely, but there may be a background app that isn't properly releasing graphics resources… – FeifanZ Aug 04 '11 at 21:05
  • Ah - I see what you mean. I've done that, yes - even with a new view & autoresizing masks, there is still flicker during rotation. Again, the flicker is just along the very top of the screen (top row of pixels). I've tried this when nothing else was running on my iPad, and when several apps are running - it doesn't seem to matter, I still see the flicker. – Rob Aug 05 '11 at 15:35
  • Hmmm...I really don't know, then. Try changing compilers, or resetting the iPad, or building with an SL machine. Try creating another app, perhaps using a different template—do you see the flickering there? – FeifanZ Aug 05 '11 at 22:23

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I faced a similar issue, it was due to setting a color/image using colorWithpatternImage: to the window.

Adi
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kee
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