斯威夫特4斯威夫特5简单的方式在一行

用法:

//MARK:- Corner Radius of only two side of UIViews
self.roundCorners(view: yourview, corners: [.bottomLeft, .topRight], radius: 12.0)

功能:

//MARK:- Corner Radius of only two side of UIViews
func roundCorners(view :UIView, corners: UIRectCorner, radius: CGFloat){
        let path = UIBezierPath(roundedRect: view.bounds, byRoundingCorners: corners, cornerRadii: CGSize(width: radius, height: radius))
        let mask = CAShapeLayer()
        mask.path = path.cgPath
        view.layer.mask = mask
}

在objective - c中

用法:

[自我。verticalSeparatorView roundCorners: UIRectCornerTopLeft | UIRectCornerTopRight半径:10 0];

在Category中使用的函数(只有一个角):

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

我不知道为什么你的解决方案没有工作，但下面的代码是为我工作。创建一个贝塞尔蒙版，并将其应用到您的视图。在下面的代码中，我将_backgroundView的底角圆角化为3个像素。self是一个自定义的UITableViewCell:

UIBezierPath *maskPath = [UIBezierPath
    bezierPathWithRoundedRect:self.backgroundImageView.bounds
    byRoundingCorners:(UIRectCornerBottomLeft | UIRectCornerBottomRight)
    cornerRadii:CGSizeMake(20, 20)
];

CAShapeLayer *maskLayer = [CAShapeLayer layer];

maskLayer.frame = self.bounds;
maskLayer.path = maskPath.CGPath;

self.backgroundImageView.layer.mask = maskLayer;

Swift 2.0版本与一些改进:

let path = UIBezierPath(roundedRect:viewToRound.bounds, byRoundingCorners:[.TopRight, .BottomLeft], cornerRadii: CGSizeMake(20, 20))
let maskLayer = CAShapeLayer()

maskLayer.path = path.CGPath
viewToRound.layer.mask = maskLayer

Swift 3.0版本:

let path = UIBezierPath(roundedRect:viewToRound.bounds,
                        byRoundingCorners:[.topRight, .bottomLeft],
                        cornerRadii: CGSize(width: 20, height:  20))

let maskLayer = CAShapeLayer()

maskLayer.path = path.cgPath
viewToRound.layer.mask = maskLayer

这里的快速扩展

Emma: . topright和。bottom right对你不起作用，可能是因为视图调用。roundCorners是在最终视图边界计算之前完成的。注意，贝塞尔路径在被调用时起源于视图边界。例如，如果自动布局将缩小视图，右侧的圆角可能在视图之外。 尝试在viewDidLayoutSubviews中调用它，其中视图的边界是final。

以下是Swift 5的最佳方法:

import UIKit

extension UIView {

func roundCorners(radius: CGFloat = 10, corners: UIRectCorner = .allCorners) {
        self.clipsToBounds = true
        self.layer.cornerRadius = radius
        if #available(iOS 11.0, *) {
            var arr: CACornerMask = []
            
            let allCorners: [UIRectCorner] = [.topLeft, .topRight, .bottomLeft, .bottomRight, .allCorners]
            
            for corn in allCorners {
                if(corners.contains(corn)){
                    switch corn {
                    case .topLeft:
                        arr.insert(.layerMinXMinYCorner)
                    case .topRight:
                        arr.insert(.layerMaxXMinYCorner)
                    case .bottomLeft:
                        arr.insert(.layerMinXMaxYCorner)
                    case .bottomRight:
                        arr.insert(.layerMaxXMaxYCorner)
                    case .allCorners:
                        arr.insert(.layerMinXMinYCorner)
                        arr.insert(.layerMaxXMinYCorner)
                        arr.insert(.layerMinXMaxYCorner)
                        arr.insert(.layerMaxXMaxYCorner)
                    default: break
                    }
                }
            }
            self.layer.maskedCorners = arr
        } else {
            self.roundCornersBezierPath(corners: corners, radius: radius)
        }
    }
    
    private func roundCornersBezierPath(corners: UIRectCorner, radius: CGFloat) {
        let path = UIBezierPath(roundedRect: bounds, byRoundingCorners: corners, cornerRadii: CGSize(width: radius, height: radius))
        let mask = CAShapeLayer()
        mask.path = path.cgPath
        layer.mask = mask
    }
    
}

这是最简单的答案:

yourView.layer.cornerRadius = 8
yourView.layer.masksToBounds = true
yourView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]

注意，如果你有布局约束附加到它，你必须在你的UIView子类中按如下方式刷新它:

override func layoutSubviews() {
    super.layoutSubviews()
    roundCorners(corners: [.topLeft, .topRight], radius: 3.0)
}

如果你不这样做，它就不会出现。

和圆角，使用扩展:

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

附加的视图控制器情况:无论你不能或不想子类化一个视图，你仍然可以舍入一个视图。通过覆盖viewWillLayoutSubviews()函数，从它的视图控制器中完成，如下所示:

class MyVC: UIViewController {
    /// The view to round the top-left and top-right hand corners
    let theView: UIView = {
        let v = UIView(frame: CGRect(x: 10, y: 10, width: 200, height: 200))
        v.backgroundColor = .red
        return v
    }()
    
    override func loadView() {
        super.loadView()
        view.addSubview(theView)
    }
    
    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()

        // Call the roundCorners() func right there.
        theView.roundCorners(corners: [.topLeft, .topRight], radius: 30)
    }
}