iOS视图部分圆角

我们都知道iOS视图圆角

[view.layer setCornerRadius:5];

但是某些需求上可能我们只需要指定View的某几个角为圆角
例如：

素材001.png

图中框出的橘色部分我们只需要左半块圆角，这种要怎么实现呢

UIRectCorner rectCorner = UIRectCornerBottomLeft | UIRectCornerTopLeft;
//任意视图
UIView *testView = [[UIView alloc] init];

UIBezierPath *bezierPath = [UIBezierPath bezierPathWithRoundedRect:testView.bounds byRoundingCorners:rectCorner cornerRadii:CGSizeMake(5, 5)];
CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
maskLayer.frame = testView.bounds;
maskLayer.path = bezierPath.CGPath;
testView.layer.mask = maskLayer;

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