Create image thumbnail with imageIO on background can make scroll smoother

gistfile1.txt

CFDataRef imageData = (__bridge CFDataRef)[self getData];
CGImageSourceRef imageSourceRef = CGImageSourceCreateWithData(imageData, nil);
CFDictionaryRef options = (__bridge CFDictionaryRef) @{
                                                               (id) kCGImageSourceCreateThumbnailWithTransform : @YES,
                                                               (id) kCGImageSourceCreateThumbnailFromImageAlways : @YES,
                                                               (id) kCGImageSourceThumbnailMaxPixelSize : @(100)};
CGImageRef imageRef = CGImageSourceCreateThumbnailAtIndex(imageSourceRef, 0 , options);
thumbnail = [UIImage imageWithCGImage: imageRef];
return thumbnail;