Sometimes you just need an empty image...

empty image.m

// Create hidden image since we can't hide/set nil the image for the search field
UIGraphicsBeginImageContext(self.frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [[UIColor clearColor] CGColor]);
CGContextFillRect(context, CGRectMake(0, 0, self.frame.size.width, self.frame.size.height));
UIImage *blankImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();