Hi all, I am new to Iphone Application Development. Recently I upgrade my Xcode 4.0.2 with IOS 4.3 to Xcode 4.2 with IOS 5. IOS 5 offer a new feauture : Automatic Reference Counting (ARC)... I just do some research on ARC, but I not sure should I use this new feature or not... Anyone is using it? Can you share some experiences and opinions about ARC with me? And one more thing is I have read from an article, it mentioned that "ARC is backwards compatible with iOS 4.0 onwards, weak references are only supported in iOS 5.0 onwards possibly another reason not to migrate everything just yet ... ". Anyone know what it really means? If I use ARC in develop my project, is the project able to install and run on a device of any IOS Version? Is it got any limitation to run my project on a IOS device? Any ideas, comments and suggestions are welcome. Thanks a lot.