Upgrading to a universal app and sdk problem

I have an iphone app.

I decided to upgrade it to iPad and installed the xcode_3.2.3_and_iphone_sdk_4__final.dmg

I upgraded the app to an universal app.

Before installation of new sdk, I could compile my iphone app with 3.0 sdk. However, after installation, I can only see iPhone Device 3.2 adn 4.0 sdks on xcode.

I wonder, if I compiled my universal app with 3.2 sdk then can the iphones with 3.0-1-2 OS versions run my new universal app?

If they can not, are there any 开发者_开发百科way to do that?

You can set in your project the iPhone OS Deployment target to fit with your app.

You find it in Project > Edit Project Settings > Build Tab > Deployment

According to Apple iPad Programming Guide:

When running on iOS 3.1.3 or earlier, your application must not use symbols introduced in iOS 3.2. For example, an application trying to use the UISplitViewController class while running in iOS 3.1 would crash because the symbol would not be available. To avoid this problem, your code must perform runtime checks to see if a particular symbol is available before using it. For information about how to perform the needed runtime checks, see “Adding Runtime Checks for Newer Symbols.”