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?

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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.

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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.

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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