objective-c : Image to NSData and Reverse Transform for saving Core Data

snippet.m

//Image to NSData and Reverse Transform for saving Core Data

//1. CoreData 모델 생성
//ex) Entities name : Photo / Attributes : date (type Date), image (type Transformable)

//2. create NSManagedObject Subclass (in this case : TWPictureDataTransformer class)

//3. TWPictureDataTransformer.h

@interface TWPictureDataTransformer : NSValueTransformer

@end


//4. TWPictureDataTransformer.m
// 이미지를 코어데이터에 저장하기 위한 클래스
// Image to NSData and Reverse Transform for saving Core Data

#import "TWPictureDataTransformer.h"

@implementation TWPictureDataTransformer


+ (Class)transformedValueClass
{
    return [NSData class]; //transform UIImage object into NSData
}


+ (BOOL)allowsReverseTransformation
{
    return YES; //allows NSData object into UIImage
}


- (id)transformedValue:(id)value
{
    return UIImagePNGRepresentation(value); //returns the data for the specified image in PNG format
}


- (id)reverseTransformedValue:(id)value
{
    UIImage *image = [UIImage imageWithData:value];
    return image; //returns the image object
}


@end