解决方案，

我改变了焦点并尝试让应用程序在我的旧ipod touch 3.1上运行

I changed focus and tried to get the app to run on my old ipod touch 3.1

我在这里找到了解决方案

I found the solution here

使用Xcode 4.2和iOS 5 SDK时是否可以定位较旧的iOS版本？

by mmorris

by mmorris

我必须做他清楚解释的事情和另外一件事：

将项目和目标构建集中的编译器设置为 LLVM GCC 4.2

这使应用程序在我的旧ipod touch和我的iphone上运行4.x。

I had to do what he clearly explained and 1 more thing:
Set the compiler in the Project and Target Build Set to LLVM GCC 4.2
That got the app running on my old ipod touch and my the iphones with 4.x.

不确定这些设置是如何从上周改变的，但我不会考虑这一点。

Not sure how any of those settings could have changed from last week, but I am not going to think about that.