Use NSURLIsExcludedFromBackupKey without crashing on iOS 5.0

Question

The check for availability seems to be working fine but I can\'t seem to set the NSURLIsExcludedFromBackupKey key without getting this crash on launch:

Answer 1

Add this line to force the symbol to be a weak import:

extern NSString * const NSURLIsExcludedFromBackupKey __attribute__((weak_import));