Since Apple announced its new next iOS5 release for iphone, there is a joy among developer community that it would be supporting garbage collection, which is not true. Actually the intention to write this blog was to give awareness to iphone developers that its not garbage collection its rather a technique called ARC(Automatic Reference Counting) that is coming in iOS5.
The major difference between garbage collection(GC) and ARC is that ARC is compile time while GC is runtime. ARC will actually insert retain and release statements in code to take care of object reference count and this done by the compiler so definitly it would reduce developer time. Unlike GC,ARC would not make device slow as it would be at compile time and not runtime.
Below is the content that copied from Apple official docs regarding ARC. Hope this post help developer in clearing their concepts
Automatic Reference Counting
Automatic Reference Counting (ARC) for Objective-C makes memory management the job of the compiler. By enabling ARC with the new Apple LLVM compiler, you will never need to type retain or release again, dramatically simplifying the development process, while reducing crashes and memory leaks. The compiler has a complete understanding of your objects, and releases each object the instant it is no longer used, so apps run as fast as ever, with predictable, smooth performance.