compare uiimage by md5 hash

compareUIImage.m

- (void)md5HashFromUIImage:(UIImage*)image
                      hash:(unsigned char*)hash
{
    CGDataProviderRef dataProvider = CGImageGetDataProvider(image.CGImage);
    NSData *data = (NSData*)CFBridgingRelease(CGDataProviderCopyData(dataProvider));
    CC_MD5([data bytes], [data length], hash);
}

- (BOOL)compareUIImages:(UIImage*)image1
                  image:(UIImage*)image2
{
    unsigned char hash1[CC_MD5_DIGEST_LENGTH];
    unsigned char hash2[CC_MD5_DIGEST_LENGTH];
    
    [self md5HashFromUIImage:image1 hash:hash1];
    [self md5HashFromUIImage:image2 hash:hash2];
    
    return memcmp(hash1, hash2, CC_MD5_DIGEST_LENGTH) == 0;
}