if convert project to Automatic Reference Counting

问题:

i not sure about convert project to Automatic Reference Counting(ARC). it still support on iOS 4.X or lower ?

thank you

回答1:

From what I can gather yes - ARC is done by the compiler and should be thought of as a wizard or helper that checks all of your code and inserts the correct retain and release statements for you.

This will therefore be compatible with older iOS runtimes.

Edit:

IT will support 4.x but not 3.x

回答2:

It will support iOS 4 but not iOS 3.

Still, there's no full support for iOS 4 since weak references only work on iOS 5. Quoting the Transitioning to ARC Release Notes directly from Apple:

ARC is supported in Xcode 4.2 for Mac OS X v10.6 and v10.7 (64-bit applications) and for iOS 4 and iOS 5. Weak references are not supported in Mac OS X v10.6 and iOS 4.