问题
Trying to keep up with the curve. I'm reading almost too much and is sending me in a tail spin. Is there a one stop link which will tell me what my target should be to run my app on all platforms based on what frameworks I have included? I make heavy use of Mapkit, and want to include iAds. My current apps seem dead on 3G.
Does Apple force you to support only the latest iOS? I have no problem with that, but not sure if someone who has and ancient 3G, how do I tell them, NO I don't support your phone, please upgrade?
回答1:
Set your project's base SDK to the latest version of the SDK. Set the deployment target to the oldest version of the OS that you plan to support. You can use features introduced in versions later than your deployment target, but you'll need to check for them before you use them, else your app will crash.
Read the release notes for each version of the OS to get a good idea of what features were introduced when. In fact, make it a habit to read the release notes thoroughly each time a new version comes out.
iOS 4.2 runs pretty well on an iPhone 3G, so there's no need to drop support for the 3G anytime soon. If your apps currently don't work on the 3G, fire up your debugger and figure out why. What version of iOS are you running on that device? Where does it crash? This is typical debugging stuff.
来源：https://stackoverflow.com/questions/5508477/i-am-using-xcode-3-2-5-i-have-iads-running-confused-about-about-targest-ios-v