有没有一种方法可以cornerRadius仅设置的左上角和右上角UIView？

我尝试了以下操作，但最终看不到该视图。

UIView *view = [[UIView alloc] initWithFrame:frame];

CALayer *layer = [CALayer layer];
UIBezierPath *shadowPath = [UIBezierPath bezierPathWithRoundedRect:frame byRoundingCorners:(UIRectCornerTopLeft|UIRectCornerTopRight) cornerRadii:CGSizeMake(3.0, 3.0)];
layer.shadowPath = shadowPath.CGPath;
view.layer.mask = layer;

请注意以下事实：如果您附加了布局约束，则必须在UIView子类中按如下所示刷新它：

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

如果您不这样做，它将不会显示。

要扩展到角落，请使用扩展名：

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
    }
}

我不确定为什么您的解决方案无效，但是以下代码对我有效。创建贝塞尔曲线蒙版并将其应用于您的视图。在下面的代码中，我_backgroundView用3个像素的半径四舍五入了的底角。self是一个习惯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版本有一些改进：

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

Swift扩展在这里

这是@JohnnyRockex答案的Swift版本

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
    }

}

view.roundCorners([.topLeft, .bottomRight], radius: 10)

注意

如果您使用的是Auto Layout，则需要将其子类化UIView并调用roundCorners视图的layoutSubviews以获得最佳效果。

class View: UIView {
    override func layoutSubviews() {
        super.layoutSubviews()

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

最后…… iOS11中有CACornerMask！使用CACornerMask它可以很容易地完成：

let view = UIView()
view.clipsToBounds = true
view.layer.cornerRadius = 10
view.layer.maskedCorners = [.layerMaxXMinYCorner, .layerMinXMinYCorner] // Top right corner, Top left corner respectively

此处的Swift代码示例：https : //stackoverflow.com/a/35621736/308315

不直接。你不得不：

1. 创建一个 CAShapeLayer
2. 将其设置path为CGPathRef基于，view.bounds但只有两个圆角（可能使用+[UIBezierPath bezierPathWithRoundedRect:byRoundingCorners:cornerRadii:]）
3. 将您view.layer.mask设为CAShapeLayer

这是一个像这样实现的简短方法：

- (void)viewDidLoad {
    [super viewDidLoad];
    UIButton *openInMaps = [UIButton new];
    [openInMaps setFrame:CGRectMake(15, 135, 114, 70)];
    openInMaps = (UIButton *)[self roundCornersOnView:openInMaps onTopLeft:NO topRight:NO bottomLeft:YES bottomRight:NO radius:5.0];
}

- (UIView *)roundCornersOnView:(UIView *)view onTopLeft:(BOOL)tl topRight:(BOOL)tr bottomLeft:(BOOL)bl bottomRight:(BOOL)br radius:(float)radius {

    if (tl || tr || bl || br) {
        UIRectCorner corner = 0;
        if (tl) {corner = corner | UIRectCornerTopLeft;}
        if (tr) {corner = corner | UIRectCornerTopRight;}
        if (bl) {corner = corner | UIRectCornerBottomLeft;}
        if (br) {corner = corner | UIRectCornerBottomRight;}

        UIView *roundedView = view;
        UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:roundedView.bounds byRoundingCorners:corner cornerRadii:CGSizeMake(radius, radius)];
        CAShapeLayer *maskLayer = [CAShapeLayer layer];
        maskLayer.frame = roundedView.bounds;
        maskLayer.path = maskPath.CGPath;
        roundedView.layer.mask = maskLayer;
        return roundedView;
    }
    return view;
}

在Swift 4.1和Xcode 9.4.1中

在iOS 11中，这一行就足够了：

detailsSubView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]//Set your view here

查看完整的代码：

//In viewDidLoad
if #available(iOS 11.0, *){
        detailsSubView.clipsToBounds = false
        detailsSubView.layer.cornerRadius = 10
        detailsSubView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
} else {
      //For lower versions
}

但是对于较低版本

let rectShape = CAShapeLayer()
    rectShape.bounds = detailsSubView.frame
    rectShape.position = detailsSubView.center
    rectShape.path = UIBezierPath(roundedRect: detailsSubView.bounds,    byRoundingCorners: [.topLeft , .topRight], cornerRadii: CGSize(width: 20, height: 20)).cgPath
    detailsSubView.layer.mask = rectShape

完整的代码是。

if #available(iOS 11.0, *){
    detailsSubView.clipsToBounds = false
    detailsSubView.layer.cornerRadius = 10
    detailsSubView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
}else{
    let rectShape = CAShapeLayer()
    rectShape.bounds = detailsSubView.frame
    rectShape.position = detailsSubView.center
    rectShape.path = UIBezierPath(roundedRect: detailsSubView.bounds,    byRoundingCorners: [.topLeft , .topRight], cornerRadii: CGSize(width: 20, height: 20)).cgPath
    detailsSubView.layer.mask = rectShape
}

如果要在情节提要中使用自动调整大小，请在viewDidLayoutSubviews（）中编写此代码。

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    if #available(iOS 11.0, *){
        detailsSubView.clipsToBounds = false
        detailsSubView.layer.cornerRadius = 10
        detailsSubView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
    }else{
        let rectShape = CAShapeLayer()
        rectShape.bounds = detailsSubView.frame
        rectShape.position = detailsSubView.center
        rectShape.path = UIBezierPath(roundedRect: detailsSubView.bounds,    byRoundingCorners: [.topLeft , .topRight], cornerRadii: CGSize(width: 20, height: 20)).cgPath
        detailsSubView.layer.mask = rectShape
    }
}

iOS 11，Swift 4
，您可以尝试以下代码：

if #available(iOS 11.0, *) {
   element.clipsToBounds = true
   element.layer.cornerRadius = CORNER_RADIUS
   element.layer.maskedCorners = [.layerMaxXMaxYCorner]
} else {
   // Fallback on earlier versions
}

您可以在表格视图单元格中使用它。

这将是最简单的答案：

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

试试这个代码，

UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view.bounds byRoundingCorners:( UIRectCornerTopLeft | UIRectCornerTopRight) cornerRadii:CGSizeMake(5.0, 5.0)];

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

view.layer.mask = maskLayer;

艾玛（Emma）：.TopRight并且.BottomRight对您不起作用，可能是因为计算view.roundCorners了最终调用之前已完成对的调用view bounds。请注意，Bezier Path派生自其调用时的视图范围。例如，如果自动布局会缩小视图范围，则右侧的圆角可能在视图范围之外。尝试在中将其称为viewDidLayoutSubviews最终视图的中调用它。

1行中的Swift 4 Swift 5简单方法

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：

[self.verticalSeparatorView roundCorners:UIRectCornerTopLeft radius:10.0];

类别中使用的功能（仅一个角）：

-(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;
    }

我的快速解决UIView和UITextFiels特定角的解决方案是使用

.layer.cornerRadius

和

layer.maskedCorners

实际的UIView或UITextFields。

例：

fileprivate func inputTextFieldStyle() {
        inputTextField.layer.masksToBounds = true
        inputTextField.layer.borderWidth = 1
        inputTextField.layer.cornerRadius = 25
        inputTextField.layer.maskedCorners = [.layerMaxXMaxYCorner,.layerMaxXMinYCorner]
        inputTextField.layer.borderColor = UIColor.white.cgColor
    }

并通过使用

.layerMaxXMaxYCorner

和

.layerMaxXMinYCorner

，我可以指定要舍入的UITextField的右上角和右下角。

您可以在此处查看结果：

斯威夫特4

extension UIView {

    func roundTop(radius:CGFloat = 5){
        self.clipsToBounds = true
        self.layer.cornerRadius = radius
        if #available(iOS 11.0, *) {
            self.layer.maskedCorners = [.layerMaxXMinYCorner, .layerMinXMinYCorner]
        } else {
            // Fallback on earlier versions
        }
    }

    func roundBottom(radius:CGFloat = 5){
        self.clipsToBounds = true
        self.layer.cornerRadius = radius
        if #available(iOS 11.0, *) {
            self.layer.maskedCorners = [.layerMaxXMaxYCorner, .layerMinXMaxYCorner]
        } else {
            // Fallback on earlier versions
        }
    }
}

以编程方式执行此操作的一种方法UIView是在UIView具有圆角的顶部上方创建一个。或者，您可以将顶部隐藏在某些东西下面。

    // Create the path (with only the top-left corner rounded)
UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view.bounds 
                           byRoundingCorners:(UIRectCornerBottomLeft | UIRectCornerBottomRight) 
                           cornerRadii:CGSizeMake(7.0, 7.0)];

// Create the shape layer and set its path
CAShapeLayer *maskLayer = [CAShapeLayer layer];
maskLayer.frame = cell.stripBlackImnageView.bounds;
maskLayer.path = maskPath.CGPath; 
// Set the newly created shapelayer as the mask for the image view's layer
view.layer.mask = maskLayer;

最简单的方法是制作带有圆角层的蒙版。

CALayer *maskLayer = [CALayer layer];
maskLayer.frame = CGRectMake(0,0,maskWidth ,maskHeight);
maskLayer.contents = (__bridge id)[[UIImage imageNamed:@"maskImageWithRoundedCorners.png"] CGImage];

aUIView.layer.mask = maskLayer;

并且不要忘记：

#import <QuartzCore/QuartzCore.h>

已经给出的所有答案都是非常好的和有效的（尤其是Yunus使用该mask属性的想法）。

但是，我需要更复杂的东西，因为我的图层可能经常更改大小，这意味着我每次都需要调用该屏蔽逻辑，这有点烦人。

我使用了swift extensions和计算属性来构建一个真实cornerRadii属性，该属性负责在布局图层时自动更新蒙版。

这是使用Peter Steinberg出色的Aspects库实现的。

完整代码在这里：

extension CALayer {
  // This will hold the keys for the runtime property associations
  private struct AssociationKey {
    static var CornerRect:Int8 = 1    // for the UIRectCorner argument
    static var CornerRadius:Int8 = 2  // for the radius argument
  }

  // new computed property on CALayer
  // You send the corners you want to round (ex. [.TopLeft, .BottomLeft])
  // and the radius at which you want the corners to be round
  var cornerRadii:(corners: UIRectCorner, radius:CGFloat) {
    get {
      let number = objc_getAssociatedObject(self, &AssociationKey.CornerRect)  as? NSNumber ?? 0
      let radius = objc_getAssociatedObject(self, &AssociationKey.CornerRadius)  as? NSNumber ?? 0
      return (corners: UIRectCorner(rawValue: number.unsignedLongValue), radius: CGFloat(radius.floatValue))
    }
    set (v) {
      let radius = v.radius
      let closure:((Void)->Void) = {
        let path = UIBezierPath(roundedRect: self.bounds, byRoundingCorners: v.corners, cornerRadii: CGSize(width: radius, height: radius))
        let mask = CAShapeLayer()
        mask.path = path.CGPath
        self.mask = mask
      }
      let block: @convention(block) Void -> Void = closure
      let objectBlock = unsafeBitCast(block, AnyObject.self)
      objc_setAssociatedObject(self, &AssociationKey.CornerRect, NSNumber(unsignedLong: v.corners.rawValue), .OBJC_ASSOCIATION_RETAIN)
      objc_setAssociatedObject(self, &AssociationKey.CornerRadius, NSNumber(float: Float(v.radius)), .OBJC_ASSOCIATION_RETAIN)
      do { try aspect_hookSelector("layoutSublayers", withOptions: .PositionAfter, usingBlock: objectBlock) }
      catch _ { }
    }
  }
}

我写了一个简单的博客文章来解释这一点。

如果您正在寻找仅适用于界面构建器的解决方案，那么有一个适用于iOS 11及更高版本的解决方案。在这里查看我的答案：https : //stackoverflow.com/a/58626264

这是使用C＃在Xamarin中为按钮的每个角设置角半径的方法：

var maskPath = UIBezierPath.FromRoundedRect(MyButton.Bounds, UIRectCorner.BottomLeft | UIRectCorner.BottomRight,
    new CGSize(10.0, 10.0));
var maskLayer = new CAShapeLayer
{
    Frame = MyButton.Bounds,
    Path = maskPath.CGPath
};
MyButton.Layer.Mask = maskLayer;

一个很好的扩展，可以重用Yunus Nedim Mehel解决方案

迅捷2.3

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

用法

let view = UIView()
view.roundCornersWithLayerMask(10,[.TopLeft,.TopRight])

更改代码后@apinho在迅速4.3工作正常

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

要使用此功能进行查看

YourViewName. roundCornersWithLayerMask(cornerRadii: 20,corners: [.topLeft,.topRight])

Stephane答案的另一个版本。

import UIKit

    class RoundCornerView: UIView {
    var corners : UIRectCorner = [.topLeft,.topRight,.bottomLeft,.bottomRight]
        var roundCornerRadius : CGFloat = 0.0
        override func layoutSubviews() {
            super.layoutSubviews()
            if corners.rawValue > 0 && roundCornerRadius > 0.0 {
                self.roundCorners(corners: corners, radius: roundCornerRadius)
            }
        }
        private 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
        }

    }

在Swift 4.2中，通过@IBDesignable如下方式创建它：

@IBDesignable

class DesignableViewCustomCorner: UIView {

    @IBInspectable var cornerRadious: CGFloat = 0 {
        didSet {
            let path = UIBezierPath(roundedRect: self.bounds, byRoundingCorners: [.topLeft, .topRight], cornerRadii: CGSize(width: cornerRadious, height: cornerRadious))
            let mask = CAShapeLayer()
            mask.path = path.cgPath
            self.layer.mask = mask
        }
    }

}

简单扩展

extension UIView {
    func roundCorners(corners: UIRectCorner, radius: CGFloat) {
        if #available(iOS 11, *) {
            self.clipsToBounds = true
            self.layer.cornerRadius = radius
            var masked = CACornerMask()
            if corners.contains(.topLeft) { masked.insert(.layerMinXMinYCorner) }
            if corners.contains(.topRight) { masked.insert(.layerMaxXMinYCorner) }
            if corners.contains(.bottomLeft) { masked.insert(.layerMinXMaxYCorner) }
            if corners.contains(.bottomRight) { masked.insert(.layerMaxXMaxYCorner) }
            self.layer.maskedCorners = masked
        }
        else {
            let path = UIBezierPath(roundedRect: bounds, byRoundingCorners: corners, cornerRadii: CGSize(width: radius, height: radius))
            let mask = CAShapeLayer()
            mask.path = path.cgPath
            layer.mask = mask
        }
    }
}

用法：

view.roundCorners(corners: [.bottomLeft, .bottomRight], radius: 12)