UIImage *image = [UIImage new]; // your button icon image
self.button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;
[self.button setImage:image forState:UIControlStateNormal];
[self.button setImage:image forState:UIControlStateHighlighted];
self.button.imageEdgeInsets = UIEdgeInsetsMake(0, self.button.frame.size.width - image.size.width, 0, 0);
self.button.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, image.size.width);