iOS UIView 单独设置一个角为圆角，两个 三个角也行

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    
    UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(100, 100, 200, 100)];
    label.backgroundColor = [UIColor blueColor];
    [self.view addSubview:label];
    
    UIRectCorner corners = UIRectCornerTopRight | UIRectCornerBottomRight;
    [label setBorderWithCornerRadius:50 borderWidth:10 borderColor:[UIColor redColor] type:corners];
    

    
}

@implementation UIView (lcAnyCorners)

- (void)setBorderWithCornerRadius:(CGFloat)cornerRadius
                      borderWidth:(CGFloat)borderWidth
                      borderColor:(UIColor *)borderColor
                             type:(UIRectCorner)corners {
    
    //    UIRectCorner type = UIRectCornerTopRight | UIRectCornerBottomRight | UIRectCornerBottomLeft;
    
    //1. 加一个layer 显示形状
    CGRect rect = CGRectMake(borderWidth/2.0, borderWidth/2.0,
                             CGRectGetWidth(self.frame)-borderWidth, CGRectGetHeight(self.frame)-borderWidth);
    CGSize radii = CGSizeMake(cornerRadius, borderWidth);
    
    //create path
    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:corners cornerRadii:radii];
    
    //create shape layer
    CAShapeLayer *shapeLayer = [CAShapeLayer layer];
    shapeLayer.strokeColor = borderColor.CGColor;
    shapeLayer.fillColor = [UIColor clearColor].CGColor;
    
    shapeLayer.lineWidth = borderWidth;
    shapeLayer.lineJoin = kCALineJoinRound;
    shapeLayer.lineCap = kCALineCapRound;
    shapeLayer.path = path.CGPath;
    
    [self.layer addSublayer:shapeLayer];
    
    
    
    
    //2. 加一个layer 按形状 把外面的减去
    CGRect clipRect = CGRectMake(0, 0,
                                 CGRectGetWidth(self.frame)-1, CGRectGetHeight(self.frame)-1);
    CGSize clipRadii = CGSizeMake(cornerRadius, borderWidth);
    UIBezierPath *clipPath = [UIBezierPath bezierPathWithRoundedRect:clipRect byRoundingCorners:corners cornerRadii:clipRadii];
    
    CAShapeLayer *clipLayer = [CAShapeLayer layer];
    clipLayer.strokeColor = borderColor.CGColor;
    shapeLayer.fillColor = [UIColor clearColor].CGColor;

    clipLayer.lineWidth = 1;
    clipLayer.lineJoin = kCALineJoinRound;
    clipLayer.lineCap = kCALineCapRound;
    clipLayer.path = clipPath.CGPath;

    self.layer.mask = clipLayer;
}

@end