How to convert CFStringRef to NSString?

Question

NSString *aNSString;
CFStringRef aCFString;
aCFString = CFStringCreateWithCString(NULL, [aNSString UTF8String], NSUTF8StringEncoding);
aCFString = CFXMLCreateStringB         


        

Answer 1

Actually, you shouldn't use Cocoa retain, release, autorelease on Core Foundation objects in generality. If you're using Garbage Collection (only on Mac OS X for now), those retain, release, autorelease calls are all no-ops. Hence memory leaks.

From Apple http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/GarbageCollection/Articles/gcCoreFoundation.html:

It is important to appreciate the asymmetry between Core Foundation and Cocoa—where retain, release, and autorelease are no-ops. If, for example, you have balanced a CFCreate… with release or autorelease, you will leak the object in a garbage collected environment:

NSString *myString = (NSString *)CFStringCreate...(...);
// do interesting things with myString...
[myString release]; // leaked in a garbage collected environment

Conversely, using CFRelease to release an object you have previously retained using retain will result in a reference count underflow error.

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PS: can't seem to comment on Peter Hosey's answer - sorry for adding my own unnecessarily.