Question

I have the following (adapted from Apple Low Level File Management – Resolving Aliases)

NSString *resolvedPath = nil;
...
resolvedPath = (NSString*)CFURLCopyFileSystemPath(resolvedUrl, kCFURLPOSIXPathStyle);
...
return resolvedPath;

Build & Analyse generates the following warning:-

194:3 Potential leak (when using garbage collection) of an object allocated on line 187 and stored into 'resolvedPath'

The detail states:-

187:32 Call to function 'CFURLCopyFileSystemPath' returns a Core Foundation object with a +1 retain count (owning reference).  Core Foundation objects are not automatically garbage collected

194:3 Object returned to caller as an owning reference (single retain count transferred to caller)

194:3 Object allocated on line 187 and stored into 'resolvedPath' and returned from method 'getTarget:' is potentially leaked when using garbage collection.  Callers of this method do not expect a returned object with a +1 retain count since they expect the object to be managed by the garbage collector

Do I have a memory leak?

If so how do I fix it?

If not how do I prevent the warnings?

Answer 1

Do I have a memory leak?

you should assume it is a leak. in GC, the allocation of a cf type is not guaranteed to be registered with the collector. GC only covers a range of types (explicit objc objects). you should assume cf types which you create or copy are not registered with the collector. whether you are returned a cftype from a cf function that is or is not registered with the collector is not disclosed (it may be because an ns type is a cf type).

If so how do I fix it?

using CFMakeCollectable or NSMakeCollectable