带有扫描指示器的条形码阅读器

我制作了@rgkobashi答案的增强版，以尝试创建正方形并为正方形内的指示器线设置动画。

扫描指示器和动画代码如下：

 func createScanningIndicator() {
    
    let height: CGFloat = 15
    let opacity: Float = 0.4
    let topColor = UIColor.green.withAlphaComponent(0)
    let bottomColor = UIColor.green

    let layer = CAGradientLayer()
    layer.colors = [topColor.cgColor, bottomColor.cgColor]
    layer.opacity = opacity
    
    let squareWidth = view.frame.width * 0.6
    let xOffset = view.frame.width * 0.2
    let yOffset = view.frame.midY - (squareWidth / 2)
    layer.frame = CGRect(x: xOffset, y: yOffset, width: squareWidth, height: height)
    
    self.view.layer.insertSublayer(layer, at: 0)

    let initialYPosition = layer.position.y
    let finalYPosition = initialYPosition + squareWidth - height
    let duration: CFTimeInterval = 2

    let animation = CABasicAnimation(keyPath: "position.y")
    animation.fromValue = initialYPosition as NSNumber
    animation.toValue = finalYPosition as NSNumber
    animation.duration = duration
    animation.repeatCount = .infinity
    animation.isRemovedOnCompletion = false
    
    layer.add(animation, forKey: nil)
}

扫描方形如下：

func createScanningFrame() {
            
    let lineLength: CGFloat = 15
    let squareWidth = view.frame.width * 0.6
    let topLeftPosX = view.frame.width * 0.2
    let topLeftPosY = view.frame.midY - (squareWidth / 2)
    let btmLeftPosY = view.frame.midY + (squareWidth / 2)
    let btmRightPosX = view.frame.midX + (squareWidth / 2)
    let topRightPosX = view.frame.width * 0.8
    
    let path = UIBezierPath()
    
    //top left
    path.move(to: CGPoint(x: topLeftPosX, y: topLeftPosY + lineLength))
    path.addLine(to: CGPoint(x: topLeftPosX, y: topLeftPosY))
    path.addLine(to: CGPoint(x: topLeftPosX + lineLength, y: topLeftPosY))

    //bottom left
    path.move(to: CGPoint(x: topLeftPosX, y: btmLeftPosY - lineLength))
    path.addLine(to: CGPoint(x: topLeftPosX, y: btmLeftPosY))
    path.addLine(to: CGPoint(x: topLeftPosX + lineLength, y: btmLeftPosY))

    //bottom right
    path.move(to: CGPoint(x: btmRightPosX - lineLength, y: btmLeftPosY))
    path.addLine(to: CGPoint(x: btmRightPosX, y: btmLeftPosY))
    path.addLine(to: CGPoint(x: btmRightPosX, y: btmLeftPosY - lineLength))

    //top right
    path.move(to: CGPoint(x: topRightPosX, y: topLeftPosY + lineLength))
    path.addLine(to: CGPoint(x: topRightPosX, y: topLeftPosY))
    path.addLine(to: CGPoint(x: topRightPosX - lineLength, y: topLeftPosY))
    
    let shape = CAShapeLayer()
    shape.path = path.cgPath
    shape.strokeColor = UIColor.white.cgColor
    shape.lineWidth = 3
    shape.fillColor = UIColor.clear.cgColor
    
    self.view.layer.insertSublayer(shape, at: 0)
}

结果如下图：