cornerRadius with border : Some glitch at border

My application is mostly round and border base. I use layer property of UIButton, UIImageView and UIView to give corner radius and border. But I am facing not clean corner problem. I am getting following results. UIButton UIImageView: You can observe a thin border line around white or grey border. This is my code: button.layer.borderWidth = 2.0; button.layer.borderColor = [[UIColor whiteColor] CGColor]; button.layer.cornerRadius = 4; button.clipsToBounds = YES; I have search to solve this but not getting success. I have tried button.layer.masksToBounds = YES but no effect. Am I missing any thing? Or is there any other method which can give me better result compare to CALayer? Comment if you need more information from me. Thanks to give your time.