问题
The Facebook iOS SDK 3.0 Beta says "These new features work with iOS 4.0 and later." Does that mean that it won't work on iOS 3.x? Does that mean that if I have an app that supports iOS 3.x, I cannot use Facebook iOS SDK 3.0?
回答1:
Correct. Facebook iOS SDK 3.0 will not work with iOS 3.x. We felt that the productivity enhancements (e.g. blocks) in iOS 4.x were simply too useful. The SDK is open source, and we plan to maintain the history, which includes the existing code that does work with 3.x. In this way there is still an option for applications that need to continue to support older versions of iOS.
回答2:
Pretty safe to say yes, you wont be able to use iOS SDK 3.0, or you will no longer be able to support iOS 3.x.
You can also interpret that to mean that you can use it on iOS 3.x, but some of the features may not work at all, in which case there is no point in changing the SDK that you use because you wont be able to take advantage of the new features.
回答3:
For what it's worth, Apple announced at WWDC 2012 that more than 80% of iOS users are using iOS 5; a further significant percentage is using iOS 4.
I realize you may have specific business needs to use 3.x, but the world is moving quickly away from 3.x (and even 4.x!) and that should factor in to your platform design.
The previous stable (non-3.0) Facebook SDK is still compatible with 3.x devices.
来源：https://stackoverflow.com/questions/11441067/will-facebook-ios-sdk-3-0-not-work-on-ios-3-x