Autorelease CFMutableDictionary

How do I autorelease a CFMutableDictionary?

I'm creating it like this:

self.mappingByMediatedObject = CFDictionaryCreateMutable(NULL, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);

And in dealloc:

self.mappingByMediatedObject = nil;
开发者_开发知识库

CoreFoundation doesn't have a notion of autorelease-- that's a Cocoa-level construct. However, for the objects that are "toll-free" bridged across worlds like strings and the collection classes, you can get the same result by casting the CF reference to its corresponding Cocoa reference, and sending it the -autorelease message, like this:

[(NSDictionary *)aDictionaryRef autorelease];

In your case, though, you might not really want to use autorelease here, because you're not handing back the reference for a Cocoa caller. Why not be a little more explicit around your allocation instead and just releasing it after setting it, like this:

CFDictionaryRef mapping = CFDictionaryCreateMutable(NULL, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
self.mappingByMediatedObject = mapping;
CFRelease(mapping);

CFDictionary and NSDictionary are toll-free bridged. This means the CoreFoundation object and its Cocoa counterpart are interchangable.

So to autorelease a CFDictionary you can write the following:

CFDictionary dict = CFDictionaryCreateMutable(...);
self.mappingByMediatedObject = dict;
[(NSDictionary*)dict autorelease];

Of course autorelease the dictionary only if your mappingByMediatedObject property retains its value (@property(retain))

As of iOS7 and Mac OS X 10.9 you can use the Core-Foundation auto release function CFAutorelease().