cocoa - How to convert CFStringRef to NSString?

Question

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

How can I get a new NSString from aCFString?

Answer 1

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.