二维码扫描并实现简单聚焦

二维码/条形码工作框图：

   输入设备 <————> 会话 <————> 输出设备      

设置扫描区域

• 特别要注意的是输出设备的属性：rectOfInterest的坐标系是横屏坐标系，因此要进行转换

1. 懒加载

    //1,输入设备
    private lazy var inputDevice:AVCaptureDeviceInput? = {
        let device = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
        return try! AVCaptureDeviceInput.init(device: device)
    }()
    //2,会话
    private lazy var session:AVCaptureSession? = {
         return AVCaptureSession.init()
    }()
    //3，输出设备，设置输出对象解析数据时聚焦的区域，默认值是全屏幕，也就是屏幕哪里扫到了二维码就聚焦哪， CGRect(x: 0, y: 0, width: 1, height: 1)，现在要求只聚焦制定框内的二维码
    private lazy var outputDevice:AVCaptureMetadataOutput? = {
       let output = AVCaptureMetadataOutput()
        // 通过对这个值的观察, 我们发现传入的是比例
        // 注意: 参照是以横屏的左上角作为, 而不是以竖屏
        // 1.获取屏幕的frame
        let viewRect = self.view.frame
        // 2.获取扫描容器的frame
        let containerRect = self.customContainerView.frame
        let x = containerRect.origin.y / viewRect.height;
        let y = containerRect.origin.x / viewRect.width;
        let width = containerRect.height / viewRect.height;
        let height = containerRect.width / viewRect.width;
        
         output.rectOfInterest = CGRect(x: x, y: y, width: width, height: height)
        
        return output
    }()
    //4,预览扫描
    private lazy var previewLayer:AVCaptureVideoPreviewLayer = {
        return AVCaptureVideoPreviewLayer.init(session: self.session)
    }()

    //5，聚焦框
    private lazy var focusLayer:CALayer = {
        var va = CALayer.init()
        return va
    }()

2.开始扫描

//二维码扫描
    func QRScanning() -> Void {
        
        //1,确认session是否可以添加输入设备
        if !(session?.canAddInput(inputDevice))!{
            return
        }
        //2,确认session是否可以添加输出设备
        if !(session?.canAddOutput(outputDevice))! {
            return
        }
        //3,添加输入输出设备
        session?.addInput(inputDevice)
        session?.addOutput(outputDevice)
        
        //4,设置输出设备能够解析的数据
        outputDevice?.metadataObjectTypes = outputDevice?.availableMetadataObjectTypes
    
        //5，设置监听输出解析到的数据，调用代理方法
        outputDevice?.setMetadataObjectsDelegate(self, queue:dispatch_get_main_queue())
        
        //6,添加预览图层,使得预览曾扫描框在一个限定范围内
        previewLayer.frame = view.frame
        view.layer.insertSublayer(previewLayer, atIndex: 0)
        
        //7，添加自定义的聚焦框
        focusLayer.frame = view.bounds
        view.layer.addSublayer(focusLayer)

        //8,开始扫描
        session?.startRunning()
    }

3.实现代理方法

extension QRBarCodeViewController:AVCaptureMetadataOutputObjectsDelegate{
    func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!)
    {
        //metadataObjects元素类型是AVMetadataObject
        guard let metadata: AVMetadataObject? = metadataObjects.last as? AVMetadataObject else{
            return
        }

        //通过预览图层将数据，转换为能识别的数据类型
        let canReadData = previewLayer.transformedMetadataObjectForMetadataObject(metadata)
        
        // DyLog(metadata)  before:corners:{ 0.5,0.6 0.6,0.6 0.6,0.3 0.5,0.3 },
        //DyLog(canReadData as! AVMetadataMachineReadableCodeObject)
        //after convert:corners:{ 162.5,309.2 166.7,401.7 260.1,401.6 258.7,307.2 },
        
        //清除之前的图层
        clearLayer()
        guard let pointArrMetaData = canReadData as? AVMetadataMachineReadableCodeObject else{
            return
        }
        //画框
        drawLine(pointArrMetaData)
        

    }
    
    
    func drawLine(data:AVMetadataMachineReadableCodeObject!) -> Void {
        

        //校验数据,查看数据的数组中是否含有corners，没有直接返回，否则会数组越界
        guard let array = data!.corners else{
            return
        }
        
        //1,创建会话图层,画贝塞尔曲线的图层CAShapeLayer
        let drawLayer = CAShapeLayer.init()
        //设置边框宽度和颜色
        drawLayer.fillColor = UIColor.clearColor().CGColor
        drawLayer.strokeColor = UIColor.greenColor().CGColor
        drawLayer.lineWidth = 3
        
        //2，创建贝塞尔曲线
        let bezierPath = UIBezierPath.init()
        var index = 0;
        //将数组中的字典转为CGPoint
        var start = CGPointZero
        CGPointMakeWithDictionaryRepresentation((array[index] as! CFDictionary), &start)
        
        bezierPath.moveToPoint(start)
        
        //3，画框
        while index < array.count-1 {
            index += 1
            DyLog(index)
            CGPointMakeWithDictionaryRepresentation((array[index] as! CFDictionary),&start)
            bezierPath.addLineToPoint(start)
        }
        //4，关闭路径
        bezierPath.closePath()
        
        //5,将贝塞尔曲线添加到图层上
        drawLayer.path = bezierPath.CGPath
        
        //6,将图层添加到聚焦界面上
        focusLayer.addSublayer(drawLayer)
    }
    
    func clearLayer() -> Void {
        guard let sublayers = focusLayer.sublayers else{
            return
        }
        for layer in sublayers {
            layer.removeFromSuperlayer()
        }
    }
}