Can I build for 4.x simulator but run in 3.x simulator?

Ok, there have been some questions alluding to this before, and I've even read some second-hand reports of people successfully doing this, but so far I haven't found a concrete answer.

Basically, I want to build an application for simulator using iOS 4.x, and then run it on a 3.x simulator.

I have both SDKs installed, so all I need is the last mile of getting the app to show up in the 3.x simulator.

I tried just copying the app across from Library/Application Support/iPhone Simulator/4.2/Applications to Library/Application Support/iPhone Simulator/3.0/Applications but it doesn't show up when I load the 3.x simulator. There's a binary plist called applicationstate.plist, which I'm guessing keeps track of what apps are install开发者_JAVA百科ed on the simulator, but I don't know what the binary format is so I'm kind of stuck at this point.

Has anyone managed to load a 4.x app onto a 3.x simulator? And if so, how did you do it?

Why are you even trying to do this? What are you trying to achieve? If what you really just want to do is ensure the app works on iOS 3.x then simply state that in xcode and don't worry about the actual simulator. The simulator could be running iOS 5.0 for all you should care as long as you have set 'iOS Deployment Target' to '3.0' in xcode's project settings. That will ensure the application is compatible with iOS 3.x and above. Obviously you then still need to ensure you're not calling methods from SDK 4.x when it will run on an iOS 3.x device. If that is what you're trying to test then what you're doing won't actually work. You should (as Apple advises) always grab hold of a real device running the target firmware version and test it on that. Grab an old iPod for example with iOS 3.x and try testing your app on that to ensure you haven't called iOS 4.x methods when running under an older firmware.

The answer is: No, you cannot build for 4.x simulator and run on a 3.1.x simulator or earlier due to fundamental changes in the way the simulator works.

The only way to test 3.x support is to either run it on a 3.x device (after setting min deployment target), or build on an older xcode that supports 3.x simulator (which isn't feasible if you use Xcode 4, except for iPad 3.2).

Note: Setting the deployment target does not test compatibility with older operating systems. It's the operating system that it actually RUNS on that matters (such as "iPhone 4.3 Simulator", "iPhone 4.0 Simulator", "iPad 3.2 Simulator", or an actual device).

Of course, now that 3.x users make up less than 10% of the total population, it's not really worth the trouble to support it anymore.