Nixwire | Business Without Wires

Out of the box, UIImage doesn’t support the NSCoding protocol which means it won’t automatically serialize if you stuff these in a dictionary or object and archive (using NSKeyedArchiver for example). The easy solution is to convert this into an NSData object which does support the protocol:

//convert from PNG to NSData, other method available for JPG
NSData *imageData = UIImagePNGRepresentation(imageToArchive);
[self.currentItem setValue:imageData forKey:@"image"];
 
//after the archived object is unarchived, you can retrieve the image like this
NSData *imageData = [currentItem valueForKey:@"image"];
if(imageData){
       UIImage *image = [UIImage imageWithData:imageData];
}

Without doing this, and trying to archive a UIImage will just result in:


-[UIImage encodeWithCoder:]: unrecognized selector sent to instance

Pretty simple. The key is the helper method UIImagePNGRepresentation found in the UIKit Function Reference.