On Aug 11, 2010, at 3:53 PM, Sandro Noël wrote:
> Greetings
>
> I'm having problems unarchiving my data in the iphone.
>
> here is the workout.
>
> 1: I archive a AttributedString to my CoreData NSData property using
> NSKeyedarchiver
> 2: Transfer the database to the iphone.
> 3: load the data using NSKeyedUnarchiver on the iphone.
> NSAttributedString *as = (NSAttributedString*)[NSKeyedUnarchiver
> unarchiveObjectWithData:attributedStringData];
>
> that crashes saying:
> -[NSKeyedUnarchiver decodeObjectForKey:]: cannot decode object of class
> (NSFont)
>
> I understand that the NSFont is UIFont on the iphone, or has similarities.
> so i implemented a Delegate method to replace the class.
> //------------------------------------------------------------------------------
> - (Class)unarchiver:(NSKeyedUnarchiver *)unarchiver
> cannotDecodeObjectOfClassName:(NSString *)name originalClasses:(NSArray
> *)classNames{
> if ([name isEqualToString:@"NSFont"])
> return [UIFont class];
>
> return nil;
> }
>
> but that never gets called because the class method does not allow for a
> delegate and instantiating the unarchiver class confuses me in how I should
> trigger the decoding once it is instantiated.
>
> Any pointers ?
You're going to run into worse problems - UIFont is not NSFont, nor can you
trivially substitute one for the other.
In general, while you can archive an NSAttributedString on OS X and unarchive
it on iOS, it's not going to work the way you want it to. Any of the
"interesting" properties that define things like appearance of the string, are
platform specific. There is no "NSForegroundAttributeName", for example, on
iOS, and even if you explicitly look for appropriate key, on OS X this will
contain an NSColor, which, of course, does not exist on iOS (and UI color is
similar, but the encoding of NSColor is undocumented, so even if you attempt to
manually handle the decoding and try to make a UIColor, it would require that
undocumented information - not to mention that there are parts of NSColor such
as color space that don't exist at all on iOS). Similarly for font
information, paragraph style (including alignment, tabs, margins), embedded
images, etc...
You might be able to get away with using CoreText and it's attributes (which
are based on CG/CT objects like CGColor and CTFont), but obviously that's not
what you're going to get from AppKits default attributed string support. So
you'll probably have to give up on using AppKit's NSAttributedString extensions
all together, and switch to the CoreText ones (and take advantage of the
CFAttributedString/NSAttributedString toll free bridging).
Glenn Andreas gandr...@gandreas.com
The most merciful thing in the world ... is the inability of the human mind to
correlate all its contents - HPL
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