Application compatibility when moving to iOS5

I work wit开发者_StackOverflow社区h iOS 4 and i want to upgrade to iOS5 to benefit of additional features. My question is, shall i be kind afraid of somethings when upgrade or there is no problem?

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I wouldn't necessarily be afraid of the upgrade at all. Though read through the documentation of changed api's first to ensure that it's a smooth transition and there are no surprises to you. I have an app and had no issues at all with the upgrade.

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In iOS5 (at least on the iPad), the UIKeyboardDidShowNotification and UIKeyboardWillHideNotification have slightly changed. So, if you do any logic whenever these notifications have been triggered, you should check whether your logic is still working.

Anyway, you can upgrade your Dev Environment and test your app in the iOS5 simulator. You should find most of the problems. Be aware that the new default compiler is LLVM which surely will give you many compile warnings, hence your source code must be slightly changed.

BTW please keep in mind that iOS5 deletes data stored in the caches directory, if it runs short of memory.

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You'll have no problems. It's really quite nifty how almost nothing breaks while gaining cool new features. I say almost because I had a small problem with a tab bar I had customized. I had inserted a UIImageView that was green to be the background. On iOS 4, to not obscure the buttons, I inserted it atIndex:0, but the same trick on iOS 5 put it below the original, black background. So I had to insert atIndex:1. But that's a hack anyway ;).

There are small quirks with different elements such as that, but it's pretty much the same. Twitter integration and Airplay improvements are great.

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Well about half of my applications had small problems but it should not take much time to fix it. In general I have more problems with X Code crashing and some strange behavior of my devices with iOS5 then with my apps.