iOS 控件切圆角

在此处看到的原文

控件如果切四个圆角的话，调用下面的代码

self.layer.cornerRadius = 2.0f  ; 
self.layer.masksToBounds = true  ; // 

如果只是切某几个角的话，调用以下的代码

 UIBezierPath * path = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:UIRectCornerTopLeft | UIRectCornerTopRight  cornerRadii:CGSizeMake(10, 10)] ;
 CAShapeLayer * sublayer  = [[CAShapeLayer alloc] init] ;   
 sublayer.frame = rect ;
 sublayer.path = path.CGPath ;
 self.layer.mask = sublayer ;

UIRectCorner的值 
typedef NS_OPTIONS(NSUInteger, UIRectCorner) {
    UIRectCornerTopLeft     = 1 << 0,
    UIRectCornerTopRight    = 1 << 1,
    UIRectCornerBottomLeft  = 1 << 2,
    UIRectCornerBottomRight = 1 << 3,
    UIRectCornerAllCorners  = ~0UL
};