iOS Development: How can I run my iPhone 4.2 app on the iPhone 3.2 simulator?

I'm diving into iOS development and I'm building a simple app that will support iOS version 3.2 to 4.2. I've tested it fairly well in the latest version of Xcode on the 4.2 simulator, but I would like to also simulate it running on a iOS 3.2 device. After reading a few tutorials on this, I managed to download and install an older version of xcode along with the older 3.2 SDK, but when I build my project in the older version of Xcode, I get a ton errors due surrounding all the iOS 4.2 functionality that the older version of Xcode doesn't support. I'm weak-linking all the 4.2 frameworks, but I'm still getting errors. How can I get my 4.2 app to build successfully in this older version of Xcode and get it to run in the 3.2 iPhone simulator?

Thanks so much for your wisdom!

Answers


You need to add #ifdef __IPHONE_4_2...#endif around any lines that reference features that only exist on 4.2. That way the 3.2 compiler will build your app as if those lines don't exist.

You need to be extremely careful to structure these statements in such a way that they exactly mirror the bits of code that would be disabled when running the built-for-4.2 build on 3.2, otherwise there's not a lot of point.

This will build your app without any of the 4.2 functionality included, so it isn't actually testing whether your weak-linking etc is correct, it's just testing how the fallback 3.2 code works.

It will probably throw up a few warnings about features/methods you didn't know didn't exist in 3.2. Make sure these have appropriate fallback code added.

(btw Apple has been known to reject iPhone apps with a Base SDK of 3.2. You need to support at least 3.1.3 if you go back before 4.0)


Did you select the option of setting the base SDK to 3.0 or others?Because by doing so you can run the new APIs available in iOS 4.2 on older OS also.

Cheers


On the second issue, of actually running it in a 3.2 version of the iPhone within the iOS simulator: I've struggled with this -- Xcode 4.0.2, set my deployment target to iOS 3.2, set my project to iPhone only, but when I try to run in the iOS Simulator under version 3.2, the simulator morphs into the iPad simulator, even if it had been running as an iPhone simulator until I selected the version number.

This frustrated me for a while. But I read this and it made sense:

http://en.wikipedia.org/wiki/IOS_version_history

The iPhone never ran 3.2; that was an iPad-only release. So, even though the Hardware > Version menu in the iOS Simulator lists 3.2 (7W367A), presumably that setting is only intended to be compatible with Hardware > Device > iPad. The simulator is enforcing this rule when it switches me into an iPad simulator. It makes complete sense.

So I'd need a 3.1.3 simulator, or older, to run my app as if running on a 3.x-generation iPhone. This isn't available in my Xcode 4 build, so it makes sense to me now that I'm just unable to do anything about this, short of putting older Xcode builds on my machine.


I think the right way to do is as follows: 1.If you are developing for version 4.2, then you must be having Xcode version 4.2 installed. 2.While building your application on devices 4.0 and 3.2 OS, select base SDK to 4.2, and deployment target device to the minimum version you want to support, say 3.2. This will make your code compatible to lower version and your application will be loaded on lower versions.

Also to support new APIs in lower versions you may follow the link : http://www.marco.org/1648550153

I hope this helps you


You can run both 3.2 and 4.x simulators in the latest Xcode (not at the same time, of course!). You have to set "Base SDK" to 4.2 and "iOS Deployment Target" to 3.2. Now you can select the 3.2 Simulator (or later) from the "Overview" popup menu in the top left corner of the project window. Also you can select the simulator version in the iOS Simulator app itself, via the "Hardware->Version" menu item.


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