How to convert a UIImage into NSData

- by

You can store a UIImage (or an NSImage on Mac) as raw data. This can be useful if you’d like to save this in Core Data.

Here’s how you convert a UIImage into NSData:

NSData *imageData = UIImagePNGRepresentation(yourImage);

To convert NSData back to a UIImage, you can do this:

UIImage *image = [[UIImage alloc]initWithData:yourData];

The UIImage class is not available on Mac OS X, but its counterpart NSImage is almost identical.

http://stackoverflow.com/questions/6476929/convert-uiimage-to-nsdata

NSValueTransformer

Core Data can convert images to and from data on the fly by using an NSValueTransformer.
Here’s one that works for images:

@implementation PatchBayTransformer

+(BOOL)allowsReverseTransformation {
    
    return YES;
}

+(Class)transformedValueClass {
    
    return [NSData class];
}

- (id)transformedValue:(id)value {
    
    // takes the UIImage into data and returns it
    NSData *imageData = UIImagePNGRepresentation(value);
    return imageData;
    
}

- (id)reverseTransformedValue:(id)value {
    
    // takes data and returns it as a UIImage
    UIImage *image = [[UIImage alloc]initWithData:value];
    return image;
}


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