ios - 如何仅在圆形 UIButton 顶部制作边框颜色？

Question

我正在 UITabBarController 中制作一个中心圆 UIButton。我只需要在 UIButton 从 tabBar 边框出来的地方绘制边框颜色。我怎样才能做到？我们只需要边框颜色 https://monosnap.com/file/7MDqGzpUdIbClvnAvAiY2kJYKUro7z

我把 UIButton 做成了

       private func setupLifelineButton() {
        let lifelineButton = UIButton(frame: CGRect(x: 0, y: 0, width: 64, height: 64))
        var lifelineButtonFrame = lifelineButton.frame
        lifelineButtonFrame.origin.y = view.bounds.height - lifelineButtonFrame.height - 13 // default without 13
        lifelineButtonFrame.origin.x = view.bounds.width / 2 - lifelineButtonFrame.size.width / 2
        lifelineButton.frame = lifelineButtonFrame
        
//        lifelineButton.backgroundColor = .redColor()
        lifelineButton.layer.cornerRadius = lifelineButtonFrame.height / 2
        lifelineButton.layer.borderWidth = 0.5
        lifelineButton.layer.borderColor = ColorManager.tabBarLayerColor.CGColor//UIColor.blackColor().CGColor
        
        lifelineButton.addTarget(self, action: #selector(menuButtonAction), forControlEvents: .TouchUpInside)
        
        // icon 
        
//        lifelineButton.setImage(UIImage(named: "LifeLineBarButtonIcon"), forState: .Normal)
        
        self.view.addSubview(lifelineButton)
        self.view.layoutIfNeeded()
    }

我需要去掉边框颜色的下半部分

Answer 1

这可能对你有帮助

objective-c

-(void)createCurveBtnWithBorder
{
   UIBezierPath *shapePath = [UIBezierPath bezierPathWithRoundedRect:_btnCurve.bounds
                                                byRoundingCorners:UIRectCornerTopLeft | UIRectCornerTopRight
                                                      cornerRadii:CGSizeMake(_btnCurve.frame.size.width/2, _btnCurve.frame.size.height/2)];

   CAShapeLayer *shapeLayer = [CAShapeLayer layer];
   shapeLayer.frame = _btnCurve.bounds;
   shapeLayer.path = shapePath.CGPath;
   _btnCurve.backgroundColor=[UIColor clearColor];
   shapeLayer.fillColor = [UIColor purpleColor].CGColor;
   shapeLayer.strokeColor = [UIColor blueColor].CGColor; //Here you can set border with green color
   shapeLayer.lineWidth = 2;
   [_btnCurve.layer addSublayer:shapeLayer];
}

swift 4

func createCurveBtnWithBorder()
{
   let shapePath = UIBezierPath(roundedRect: btnCurve.bounds, byRoundingCorners: [.topLeft, .topRight], cornerRadii: CGSize(width: btnCurve.frame.size.width / 2, height: btnCurve.frame.size.height / 2))
   let shapeLayer = CAShapeLayer()
   shapeLayer.frame = btnCurve.bounds
   shapeLayer.path = shapePath.cgPath
   btnCurve.backgroundColor = UIColor.clear as? CGColor
   shapeLayer.fillColor = UIColor.purple.cgColor
   shapeLayer.strokeColor = UIColor.blue.cgColor
   //Here you can set border with green color
   shapeLayer.lineWidth = 2
   btnCurve.layer.addSublayer(shapeLayer)
}

这是输出