Category to add CSS border-radius style corner radii, where you can specify which corners to round.

UIView+Corners.h

@interface UIView(Corners)

- (void)cornerRadius:(float)radius forCorners:(UIRectCorner)corners;

@end

UIView+Corners.m

#import <QuartzCore/QuartzCore.h>
#import "UIView+Corners.h"

@implementation UIView(Corners)

-(void)cornerRadius:(float)radius forCorners:(UIRectCorner)corners{
  CAShapeLayer* mask = [CAShapeLayer layer];
  mask.path = [UIBezierPath bezierPathWithRoundedRect:self.bounds
                                    byRoundingCorners:corners
                                          cornerRadii:CGSizeMake(radius, radius)].CGPath;
  self.layer.mask = mask;
}

@end