Mixing garbage collected framework with normal code

Question

I know my way around Objective-C and I have experience with garbage collection from .NET, although I never used it in objective-c. I write my code without using it.

Now I'm thinkig about using one of the frameworks (Blocks) which is available as GC-only. My question is - can I still use the framework without any changes to my current non-GC code and without using GC myself?

Answer 1

A process is either GC or non-GC. That is, all Objective-C will either always be GC'd or will never be GC'd. There is no mixing of the two memory models in a single process. You cannot mix a GC only framework with a non-GC only framework.

When building a framework, you can set GC to "supported" at which point in time the framework could be used in either a GC'd or a non-GC'd process. However, you will have to maintain correctness for both running environments separately.

What is this "Blocks" framework to which you refer? If you are talking about Blocks, the language feature shipped in Snow Leopard's Objective-C, then it works just fine under both GC and non-GC.

Answer 2

As stated in the garbage collection programming guide, "Code compiled as GC Required is presumed to not use traditional Cocoa retain/release methods and may not be loaded into an application that is not running with garbage collection enabled."

So no, unfortunately. But how much work it would be to adopt garbage collection depends on your app. You might try testing to see if it looks like a big project. (It often is, but sometimes it's not so bad.)