How can I save cvMat in CoreData on iOS?

I am using CoreData in my project. I can save UIImage by using UIImageToDataTransformer class in my project. Also I am using opencv library and I need to save some cvMat struct (they are structs, right?). I have read some posts about transformable but still cant figure out how to save it in coredata and fetch it back.

I have one entity called "Human" and it has a attribute called ProjVal and its type is transformable which holds data of cvMat.

What should my next step be?

Below its the transformer class for UIImage but how can I transform cvMat's data? Thank for your advices.

#import "UIImageToDataTransformer.h"
@implementation UIImageToDataTransformer

+ (BOOL)allowsReverseTransformation {
    return YES;
}

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

- (id)transformedValue:(id)value {
    return UIImagePNGRepresentation(value);
}

- (id)reverseTransformedValue:(id)value {
    return [[[UIImage alloc] initWithData:value] autorelease];
}
@end

Edit: Is it a better way to use its type as Binary Data type instead Transformable type? Im using auto-created classes for my entities.

I use this code while saving

CvMat *mat = cvCreateMat(3, 3, CV_32FC1);
for (int i=0; i<9; i++) {
    mat->data.fl[i] = 1.0f;
}


NSData *projValData = [[NSData alloc] initWithBytes:&mat length:sizeof(mat)];
human.projVal = projValData;

and while reading it back:

CvMat *mat;
NSData *data =  [[humansArray objectAtIndex:0] projVal];
memcpy(&mat,[data bytes],[data length]);
if (mat) {
    NSLog(@"if mat works");
    for (int i=0; i<9; i++) {
        NSLog(@"%f",mat->data.fl[i]);
    }
}

it doesnt work well and crashed in for loop. Where is my mistake?

Can you get a pointer to (and size of) the raw bytes of your cvMat data?

If so, you can use the dataWithBytes:length: class method of NSData to in your transformedValue: implementation and the bytes (instance) method in reverseTransformedValue:.