I found in xcode4.2, there is only ios5.0 & 4.3 simulator exist. My product should support ios4.0+. How can I install the ios4.0 simulator?
Thank you.
Download http://developer.apple.com/ios/download.action?path=/iphone/iphone_sdk_4__final/xcode_3.2.3_and_iphone_sdk_4__final.dmg and install the packages you want on your Developer folder.
Here's step by step on how to do it on Xcode 3.5 but it shouldn't change much from Xcode 4 http://chris-fletcher.com/2010/08/28/howto-install-iphone-sdk-2-0-3-1-for-xcode-3-2/
Short answer, You can't. There is not support.
Also the simulator does not replace real device testing. If something work in the simulator does not mean it work on a device.
My advice, get a device with iOS 4.0 and use that for debuging/testing the app for iOS 4.0.