You have to edit your method as
if (iref) {
dispatch_async(dispatch_get_main_queue(), ^{
cell.image.image = [UIImage imageWithCGImage:iref scale:[rep scale] orientation:(UIImageOrientation)[rep orientation]];
});
}
This above code will retrieve the asset images with their captured/original orientation.
You have to update the user interface on main thread for better performance. So you have to use either
dispatch_async(dispatch_get_main_queue()
or
performSelectorOnMainThread