@interface CJScanQRCodeViewController () <AVCaptureMetadataOutputObjectsDelegate>@property (strong, nonatomic) AVCaptureDevice * device; //捕获设备，默认后置摄像头
@property (strong, nonatomic) AVCaptureDeviceInput * input; //输入设备
@property (strong, nonatomic) AVCaptureMetadataOutput * output;//输出设备，需要指定他的输出类型及扫描范围
@property (strong, nonatomic) AVCaptureSession * session; //AVFoundation框架捕获类的中心枢纽，协调输入输出设备以获得数据
@property (strong, nonatomic) AVCaptureVideoPreviewLayer * previewLayer;//展示捕获图像的图层，是CALayer的子类@property (strong, nonatomic) UIPinchGestureRecognizer *pinchGes;//缩放手势
@property (assign, nonatomic) CGFloat scanRegion_W;//二维码正方形扫描区域的宽度，根据不同机型适配@end

- (void)viewDidLoad {[super viewDidLoad];//页面标题self.title = @"扫一扫";//配置定位信息[self configLocation];//配置二维码扫描[self configBasicDevice];//配置缩放手势[self configPinchGes];//开始启动[self.session startRunning];
}

- (void)configBasicDevice{//默认使用后置摄像头进行扫描,使用AVMediaTypeVideo表示视频self.device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];//设备输入 初始化self.input = [[AVCaptureDeviceInput alloc]initWithDevice:self.device error:nil];//设备输出 初始化，并设置代理和回调，当设备扫描到数据时通过该代理输出队列，一般输出队列都设置为主队列，也是设置了回调方法执行所在的队列环境self.output = [[AVCaptureMetadataOutput alloc]init];[self.output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];//会话 初始化，通过 会话 连接设备的 输入 输出，并设置采样质量为 高self.session = [[AVCaptureSession alloc]init];[self.session setSessionPreset:AVCaptureSessionPresetHigh];//会话添加设备的 输入 输出，建立连接if ([self.session canAddInput:self.input]) {[self.session addInput:self.input];}if ([self.session canAddOutput:self.output]) {[self.session addOutput:self.output];}//指定设备的识别类型 这里只指定二维码识别这一种类型 AVMetadataObjectTypeQRCode//指定识别类型这一步一定要在输出添加到会话之后，否则设备的课识别类型会为空，程序会出现崩溃[self.output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];//设置扫描信息的识别区域，本文设置正中央的一块正方形区域，该区域宽度是scanRegion_W//这里考虑了导航栏的高度，所以计算有点麻烦，识别区域越小识别效率越高，所以不设置整个屏幕CGFloat navH = self.navigationController.navigationBar.bounds.size.height;CGFloat viewH = ZYAppHeight - navH;CGFloat scanViewH = self.scanRegion_W;[self.output setRectOfInterest:CGRectMake((ZYAppWidth-scanViewH)/(2*ZYAppWidth), (viewH-scanViewH)/(2*viewH), scanViewH/ZYAppWidth, scanViewH/viewH)];//预览层 初始化，self.session负责驱动input进行信息的采集，layer负责把图像渲染显示//预览层的区域设置为整个屏幕，这样可以方便我们进行移动二维码到扫描区域,在上面我们已经对我们的扫描区域进行了相应的设置self.previewLayer = [[AVCaptureVideoPreviewLayer alloc]initWithSession:self.session];self.previewLayer.frame = CGRectMake(0, 0, ZYAppWidth, ZYAppHeight);self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;[self.view.layer addSublayer:self.previewLayer];//扫描框 和扫描线的布局和设置，模拟正在扫描的过程，这一块加不加不影响我们的效果，只是起一个直观的作用TNWCameraScanView *clearView = [[TNWCameraScanView alloc]initWithFrame:self.view.frame navH:navH];[self.view addSubview:clearView];//扫描框下面的信息label布局UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, (viewH+scanViewH)/2+10.0f, ZYAppWidth, 20.0f)];label.text = @"扫一扫功能仅用于会议签到";label.font = FONT(15.0f);label.textColor = [UIColor whiteColor];label.textAlignment = NSTextAlignmentCenter;[self.view addSubview:label];
}

- (void)configPinchGes{self.pinchGes = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchDetected:)];[self.view addGestureRecognizer:self.pinchGes];
}- (void)pinchDetected:(UIPinchGestureRecognizer*)recogniser{if (!_device){return;}//对手势的状态进行判断if (recogniser.state == UIGestureRecognizerStateBegan){_initScale = _device.videoZoomFactor;}//相机设备在改变某些参数前必须先锁定，直到改变结束才能解锁NSError *error = nil;[_device lockForConfiguration:&error]; //锁定相机设备if (!error) {CGFloat zoomFactor; //缩放因子CGFloat scale = recogniser.scale;if (scale < 1.0f) {zoomFactor = self.initScale - pow(self.device.activeFormat.videoMaxZoomFactor, 1.0f - recogniser.scale);} else {zoomFactor = self.initScale + pow(self.device.activeFormat.videoMaxZoomFactor, (recogniser.scale - 1.0f) / 2.0f);}zoomFactor = MIN(15.0f, zoomFactor);zoomFactor = MAX(1.0f, zoomFactor);_device.videoZoomFactor = zoomFactor;[_device unlockForConfiguration];}
} 

#pragma mark - AVCaptureMetadataOutputObjectsDelegate
//后置摄像头扫描到二维码的信息
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{[self.session stopRunning];   //停止扫描if ([metadataObjects count] >= 1) {//数组中包含的都是AVMetadataMachineReadableCodeObject 类型的对象，该对象中包含解码后的数据AVMetadataMachineReadableCodeObject *qrObject = [metadataObjects lastObject];//拿到扫描内容在这里进行个性化处理NSString *result = qrObject.stringValue;//解析数据进行处理并实现相应的逻辑//代码省略
}