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
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>
其他回答
简单的扩展
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)
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
所有已经给出的答案都是非常好的和有效的(特别是尤努斯使用蒙版属性的想法)。
然而，我需要一些更复杂的东西，因为我的层可以经常改变大小，这意味着我需要每次都调用掩蔽逻辑，这有点烦人。
我使用了swift扩展和计算属性来构建一个真正的cornerRadii属性，它负责在图层布局时自动更新蒙版。
这是使用Peter Steinberg伟大的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 _ { }
}
}
}
我写了一篇简单的博客来解释这一点。
在swift 4.3中，修改代码后@apinho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
}
}
为您的视图使用此函数
YourViewName. roundCornersWithLayerMask(cornerRadii: 20,corners: [.topLeft,.topRight])
对于 SwiftUI
我找到了这些解决方案，你可以在这里查看https://stackoverflow.com/a/56763282/3716103
我强烈推荐第一个
选项1:使用Path + GeometryReader
(更多关于GeometryReader的信息:https://swiftui-lab.com/geometryreader-to-the-rescue/)
struct ContentView : View {
var body: some View {
Text("Hello World!")
.foregroundColor(.white)
.font(.largeTitle)
.padding(20)
.background(RoundedCorners(color: .blue, tl: 0, tr: 30, bl: 30, br: 0))
}
}
RoundedCorners
struct RoundedCorners: View {
var color: Color = .white
var tl: CGFloat = 0.0
var tr: CGFloat = 0.0
var bl: CGFloat = 0.0
var br: CGFloat = 0.0
var body: some View {
GeometryReader { geometry in
Path { path in
let w = geometry.size.width
let h = geometry.size.height
// Make sure we do not exceed the size of the rectangle
let tr = min(min(self.tr, h/2), w/2)
let tl = min(min(self.tl, h/2), w/2)
let bl = min(min(self.bl, h/2), w/2)
let br = min(min(self.br, h/2), w/2)
path.move(to: CGPoint(x: w / 2.0, y: 0))
path.addLine(to: CGPoint(x: w - tr, y: 0))
path.addArc(center: CGPoint(x: w - tr, y: tr), radius: tr, startAngle: Angle(degrees: -90), endAngle: Angle(degrees: 0), clockwise: false)
path.addLine(to: CGPoint(x: w, y: h - be))
path.addArc(center: CGPoint(x: w - br, y: h - br), radius: br, startAngle: Angle(degrees: 0), endAngle: Angle(degrees: 90), clockwise: false)
path.addLine(to: CGPoint(x: bl, y: h))
path.addArc(center: CGPoint(x: bl, y: h - bl), radius: bl, startAngle: Angle(degrees: 90), endAngle: Angle(degrees: 180), clockwise: false)
path.addLine(to: CGPoint(x: 0, y: tl))
path.addArc(center: CGPoint(x: tl, y: tl), radius: tl, startAngle: Angle(degrees: 180), endAngle: Angle(degrees: 270), clockwise: false)
}
.fill(self.color)
}
}
}
RoundedCorners_Previews
struct RoundedCorners_Previews: PreviewProvider {
static var previews: some View {
RoundedCorners(color: .pink, tl: 40, tr: 40, bl: 40, br: 40)
}
}
