Key for the remainder of the HTTP status line following the status code, returned as an NSString object.
This string usually contains an explanation of the error in English. Because this string is taken straight from the server response, it’s not localized.
Available in Mac OS X v10.0 and later.
Declaration Syntax Version Information- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)