UIImage and NSCoding

Here is a category to conform  UIImage to  NSCoding so you can archive it. This is untested - I hacked this up a few minutes in response to a question posed on Twitter. Please let me know if it needs any corrections:

UIImage-NSCoding.h

//
//  UIImage-NSCoding.h

#import <Foundation/Foundation.h>

@interface UIImageNSCoding <NSCoding>
- (id)initWithCoder:(NSCoder *)decoder;
- (void)encodeWithCoder:(NSCoder *)encoder;
@end

UIImage-NSCoding.m

//
//  UIImage-NSCoding.m

#import "UIImage-NSCoding.h"
#define kEncodingKey        @"UIImage"

@implementation UIImage(NSCoding)
- (id)initWithCoder:(NSCoder *)decoder
{
    if ((self = [super init]))
    { NSData *data = [decoder decodeObjectForKey:kEncodingKey]; self = [self initWithData:data]; }
    
    return self;
}
- (void)encodeWithCoder:(NSCoder *)encoder
{
    NSData *data = UIImagePNGRepresentation(self);
    [encoder encodeObject:data forKey:kEncodingKey];
}
@end

This is also checked into  Google Code if you prefer to grab it from there.