NSString and CFStringRef are “Toll free bridged”, meaning that you can simply typecast between them.
For example:
CFStringRef aCFString = (CFStringRef)aNSString;
works perfectly and transparently. Likewise:
NSString *aNSString = (NSString *)aCFString;
The previous syntax was for MRC. If you’re using ARC, the new casting syntax is as follows:
NSString *aNSString = (__bridge NSString *)aCFString;
works as well. The key thing to note is that CoreFoundation will often return objects with +1 reference counts, meaning that they need to be released (all CF[Type]Create format functions do this).
The nice thing is that in Cocoa you can safely use autorelease or release to free them up.