when deploying an iOS app for an older SDK, how to test it?

I have written an app and its base SDK is set to 4.2, and at the moment it is in the app store with a deployment target set to 4.2, I'm sure you'll agree this is a bad idea because I a开发者_StackOverflow中文版m alienating all potential users who do not have the latest version of iOS installed.

So my question is, when deploying for an older version of iOS, how do I make sure it will run, i.e. how do I check whether I've used any modern API's that are not present in the deployment target iOS version?

The only sure-fire way to make sure your app will run is to test on a device running the older OS version you specify.

Even old versions of the iPhone Simulator (if you can find such) will not do a good job of checking for compatibility.

Most developers who want to support customers on iPhoneOS 3.x have access to an old test device, such as an used iPod Touch (hand-me-down, or purchased on eBay, etc.) running the OS version set in the app's Deployment Target. Otherwise, the developer is just guessing/gambling.

Check the documentation of the libraries or methods you are using. Test on the actually device installed with the version of the OS you wish to support.

Change the Base sdk version to 4.2, target sdk to 3.0 or any. test the app in simulator as the target as simulator 3.0 r any.

But, when compared to 3.2 , 4.2 version has many new functionalities that do not work on 3.2 version devices. So take respective steps to do for 3.2 r for 4.2.

The better idea is to find the version of the device , then give the accessibility based on the version.

Thanks, Bharath