问题
I have submit my app in app store successfully and got approve from apple but the app Development Targer is 5.0 and developed in Xcode 4.2.1(mac os x). So its not installed in IOS 4 devices from app store, now how can i solve this problem and get run on all (i.e) from IOS 3 devices.
回答1:
You will need to set the deployment target to whatever minimum iOS version you want to target. You can set this in your Project's Target, as in the screenshot below:

However, it's a good idea to keep the Base SDK at the latest released version; which is currently 5.1:

Note, in order for people to now be able to download your app on the new minimum version, you will need to reupload a new binary to the App Store for review and acceptance.
回答2:
if i'm not wrong you need to rebuild you application and then resubmit it to apple again .
as i know there is no other way to change the target devices..
hope this helps..
回答3:
Try this U can surely get out this error
In your project -> build settings -> architectures, try adding an arm6 architecture
in architectures add both armv6 and armv7
来源:https://stackoverflow.com/questions/10414712/iphone-app-development-target-change-in-xocde4-2-1