Archiving Notes

There is a preliminary implementation of NSKeyedArchiver and NSKeyedUnarchiver which should be compatible with the OS X version.

  • NSKeyedUnarchiver reads the entire plist into memory before constructing the object graph, it should construct it incrementally as does Foundation on OS X

  • Paths that raise errors vs. calling _fatalError() need to be reviewed carefully

  • The signature of the decoding APIs that take a class whitelist has changed from NSSet to [AnyClass] as AnyClass does not support Hashable. The API change has been marked Experimental.

  • classForKeyed[Un]Archiver has moved into NSObject so it can be overridden, move this back into an extension eventually



  • NSArray
  • NSCalendar
  • NSCFArray (encodes as NSArray)
  • NSCFDictionary (encodes as NSDictionary)
  • NSCFSet (encodes as NSSet)
  • NSCFString (encodes as NSString)
  • NSConcreteValue
  • NSData
  • NSDate
  • NSDictionary
  • NSError
  • NSLocale
  • NSNotification
  • NSNull (no-op)
  • NSOrderedSet
  • NSPersonNameComponents
  • NSPort (not supported for keyed archiving)
  • NSSet
  • NSSpecialValue (for limited number of types)
  • NSString
  • NSTimeZone
  • NSValue (via class cluster hack)


Pending actual class implementation

  • NSAttributedString

Pending coder implementation

  • NSAffineTransform
  • NSCharacterSet
  • NSDecimalNumber
  • NSDecimalNumberHandler
  • NSExpression
  • NSIndexPath
  • NSIndexSet
  • NSPredicate
  • NSSortDescriptor
  • NSTextCheckingResult
  • NSURLAuthenticationChallenge
  • NSURLCache
  • NSURLCredential
  • NSURLProtectionSpace
  • NSURLRequest