如何设置cornerRadius只用于UIView的左下角,右下角和左上角？

Question

有没有办法只为UIView的左下角,右下角和左上角设置cornerRadius？

我尝试了下面这个,但最终让视图消失了.下面的代码有什么问题吗？

    UIBezierPath *maskPath;
    maskPath = [UIBezierPath bezierPathWithRoundedRect:view.bounds byRoundingCorners:(UIRectCornerBottomLeft | UIRectCornerBottomRight) cornerRadii:CGSizeMake(20.0, 20.0)];
    CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
    maskLayer.path = maskPath.CGPath;
    view.layer.mask = maskLayer;

Answer 1

你可以这样做:

UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:self.viewOutlet.bounds byRoundingCorners:(UIRectCornerTopLeft | UIRectCornerBottomLeft | UIRectCornerBottomRight) cornerRadii:CGSizeMake(10.0, 10.0)];

CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
maskLayer.frame = self.view.bounds;
maskLayer.path  = maskPath.CGPath;
self.viewOutlet.layer.mask = maskLayer;

更新:
如果您需要边框,只需创建另一个CAShapeLayer并将其添加到视图的图层作为子图层.像这样(将此代码放在上面的代码下面):

CAShapeLayer *borderLayer = [[CAShapeLayer alloc] init];
borderLayer.frame = self.view.bounds;
borderLayer.path  = maskPath.CGPath;
borderLayer.lineWidth   = 4.0f;
borderLayer.strokeColor = [UIColor blackColor].CGColor;
borderLayer.fillColor   = [UIColor clearColor].CGColor;

[self.viewOutlet.layer addSublayer:borderLayer];

在swift 3.0中像这样:

let maskPath = UIBezierPath.init(roundedRect: self.viewOutlet.bounds, byRoundingCorners:[.topLeft, .bottomLeft], cornerRadii: CGSize.init(width: 10.0, height: 10.0))
let maskLayer = CAShapeLayer()
maskLayer.frame = self.viewOutlet.bounds
maskLayer.path = maskPath.cgPath
self.viewOutlet.layer.mask = maskLayer

Answer 2

在xcode 8和swift 3中测试过

extension UIView {
    func roundCorners(corners:UIRectCorner, radius: CGFloat) {
      let path = UIBezierPath(roundedRect: self.bounds, byRoundingCorners: corners, cornerRadii: CGSize(width: radius, height: radius))
      let mask = CAShapeLayer()
      mask.path = path.cgPath
      self.layer.mask = mask
    }
}

并使用这样的

YourView.roundCorners([.topLeft, .bottomLeft], radius: 10)

Answer 3

使用自定义UIView并实现以下代码

#import "CustomUIView.h"

@implementation CustomView

- (void)drawRect:(CGRect)rect
{
    // Drawing code
    CAShapeLayer * maskLayer = [CAShapeLayer layer];
    maskLayer.path = [UIBezierPath bezierPathWithRoundedRect: self.bounds byRoundingCorners: UIRectCornerTopLeft | UIRectCornerBottomLeft | UIRectCornerBottomRight cornerRadii: (CGSize){20.0, 20.0}].CGPath;

    self.layer.mask = maskLayer;
}

@end

输出:

看看UIBezierPath.h选项:

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

Answer 4

设置视图的角半径 Swift

层的创建和屏蔽应该在drawRect()继承自的可选块内部运行UIView

    override func drawRect(rect: CGRect) {
        super.drawRect(rect)

        let maskPath = UIBezierPath(roundedRect: self.view.bounds, byRoundingCorners: [.TopLeft, .BottomLeft, .BottomRight], cornerRadii: CGSizeMake(10, 10))
        let maskLayer = CAShapeLayer()
        maskLayer.frame = self.view.bounds
        maskLayer.path  = maskPath.CGPath
        self.view.layer.mask = maskLayer
    }