Re: Objective-C Garbage Collection problems
Re: Objective-C Garbage Collection problems
- Subject: Re: Objective-C Garbage Collection problems
- From: Quincey Morris <email@hidden>
- Date: Mon, 8 Mar 2010 18:25:41 -0800
On Mar 8, 2010, at 16:01, Josh de Lioncourt wrote:
> 1. I have a project which uses an open source framework which is already compiled.
>
> 2. The open source framework, in its own Xcode project, compiles just fine whether Objective-C garbage colection is set to supported or unsupported. No problems.
>
> 3. In my project, (a very very simple project meant for example purposes), everything compiles and runs just fine if garbage collection is set to "unsupported".
>
> 4. When garbage collection is supported, everything builds, but I receive this message when the app launches:
> GDB: Data Formatters temporarily unavailable, will re-try after a 'continue'. (Not safe to call dlopen at this time.)
>
> I'm exceptionally confused. I don't actually think the framework is the problem. The code compiles and runs fine when garbage collection is unsupported, so I don't think there's anything wrong there either.
It's not entirely clear how the framework has been written. If your application is set to use garbage collection, then it requires its frameworks to use garbage collection too. In that case, you must:
-- Build the framework with its GC build setting set to 'supported' or 'required'. This causes the compiler to emit object code that's aware of strong and weak references, for example.
-- Ensure that the framework actually has source code to support GC. This involves arranging for references to objects and GC memory to be maintained so as to give them proper lifetimes. The compiler can't do that for you, in general.
Therefore, if the framework isn't coded for GC compatibility, it's likely going to be unusable at runtime in a GC app, no matter how you set the build settings.
Was the framework written with code for both GC and non-GC environments?
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