有没有办法为一个UIView的左上角和右上角设置角半径?

我尝试了下面的方法,但最终它再也看不到视图了。

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;

当前回答

一种编程的方法是创建一个UIView在UIView顶部有圆角的部分。或者你可以把顶部藏在什么东西下面。

其他回答

这是如何在c#中使用Xamarin为按钮的每个角落设置角半径:

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;

Stephane回答的另一个版本。

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
        }

    }

下面是一个实现的简短方法:

- (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;
}

最后,在iOS11中有CACornerMask ! 使用CACornerMask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

最简单的方法是用圆角层做一个蒙版。

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

aUIView.layer.mask = maskLayer;

别忘了:

#import <QuartzCore/QuartzCore.h>