cocoastringcfstring

How to convert CFStringRef to NSString?

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

How can I get a new NSString from aCFString?

Solution

  • 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.