NSURL.fileSystemRepresentation implementation

As far as I understand NSURL is responsible for deallocating memory to
which UnsafePointer returned from NSURL.fileSystemRepresentation points to.
Could one use private buffer to store result
for NSURL.fileSystemRepresentation or layout of this class should be the
same as CFURL?
Also NSFileManager has similar method fileSystemRepresentationWithPath, but
I'm not sure about it because it allocates memory that is not freed in
case of success.