cast of Objective-C pointer type 'NSString *' to C pointer type 'CFStringRef' (aka 'const struct __CFString *') requires a bridged cast

Question

When converting an Objective-C program to a Objective-C ARC, I get the error:

\"cast of Objective-C pointer type \'NSString *\' to C pointer type \'CFStringR         


        

Answer 1

Have a look at the ARC documentation on the LLVM website. You'll have to use __bridge or one of the other keywords.

This is because Core Foundation objects (CF*Refs) are not controlled by ARC, only Obj-C objects are. So when you convert between them, you have to tell ARC about the object's ownership so it can properly clean them up. The simplest case is a __bridge cast, for which ARC will not do any extra work (it assumes you handle the object's memory yourself).