首先需要: import AVFoundation

// MARK: - 1.懒加载: 会话,输入设备,输出设备,预览图层

//会话

private lazy var session: AVCaptureSession = AVCaptureSession()

//拿到输入设备

private lazy var deviceInput: AVCaptureDeviceInput? = {

//获取摄像头

let device = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)

do {

//创建输入对象

let input = try AVCaptureDeviceInput(device: device)

return input

} catch {

//打印错误信息

print(error)

return nil

}

}()

//拿到输出设备

private lazy var output: AVCaptureMetadataOutput = AVCaptureMetadataOutput()

//创建预览图层

private lazy var previewLayer: AVCaptureVideoPreviewLayer = {

let layer = AVCaptureVideoPreviewLayer(session: self.session)

layer.frame = UIScreen.mainScreen().bounds

return layer

}()

//MARK: - 2.扫描二维码

func starScan() {

//先判断是否能将设备添加到回话中

if !session.canAddInput(deviceInput) {

return

}

//判断是否能够将输出添加到回话中

if !session .canAddOutput(output) {

return

}

//将输入和输出添加到回话中

session.addInput(deviceInput)

session.addOutput(output)

//设置输入能够解析的数据类型

//设置能解析的数据类型,一定要在输出对象添加到会员之后设置

output.MetadataObjectTypes = output.availableMetadataObjectTypes

//设置输出对象的代理,只要解析成功,就会通知代理

output.setMetadataObjectsDelegate(self,queue: dispatch_get_main_queue())

//添加预览图层

view.layer.insertSublayer(previewLayer,atIndex: 0)

//告诉session开始扫描

session.startRunning()

}

//MARK: - 3.实现代理 AVCaptureMetadataOutputObjectsDelegate

extension QRCodeViewController: AVCaptureMetadataOutputObjectsDelegate {

//只要解析到数据就会调用

func captureOutput(captureOutput: AVCaptureOutput!,didOutputMetadataObjects MetadataObjects: [AnyObject]!,fromConnection connection: AVCaptureConnection!) {

//获取扫描结果

//注意是: stringValue

print(MetadataObjects.last?.stringValue)

}

}