#import <AVFoundation/AVFoundation.h>
<AVCaptureMetadataOutputObjectsDelegate>

@property (strong,nonatomic)AVCaptureDevice * device;
@property (strong,nonatomic)AVCaptureDeviceInput * input;
@property (strong,nonatomic)AVCaptureMetadataOutput * output;
@property (strong,nonatomic)AVCaptureSession * session;
@property (weak, nonatomic) IBOutlet UIView *outputView;//xib中扫描的View
@property (strong,nonatomic)AVCaptureVideoPreviewLayer * preview;
@property (strong, nonatomic) NSTimer * timer;//为了做扫描动画的定时器
@property (strong, nonatomic) UIImageView * lineImage;//扫描动画的横线

-(UIImageView *)lineImage{
 if (!_lineImage) {
  CGFloat outputW = self.outputView.frame.size.width;
  _lineImage = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0,outputW, 2)];
  _lineImage.image = [UIImage imageNamed:@"ray"];
 }
 return _lineImage;
}

-viewDidLoad{
[super viewDidLoad];
 // Device
 _device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

 // Input
 _input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];

 // Output
 _output = [[AVCaptureMetadataOutput alloc]init];
 [_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];

 // Session
 _session = [[AVCaptureSession alloc]init];
 [_session setSessionPreset:AVCaptureSessionPresetHigh];
 //连接输入和输出
 if ([_session canAddInput:self.input])
 {
  [_session addInput:self.input];
 }

 if ([_session canAddOutput:self.output])
 {
  [_session addOutput:self.output];
 }
//设置条码类型
 _output.metadataObjectTypes =@[AVMetadataObjectTypeQRCode];

 //设置条码位置
 CGFloat X = (ScreenW/2-100)/ScreenW;
 CGFloat Y = (ScreenH/2-100)/ScreenH;
 CGFloat W = 200/ScreenW;
 CGFloat H = 200/ScreenH;
 //设置扫描范围（注意，X与Y交互，W与H交换）
 [_output setRectOfInterest:CGRectMake(Y, X, H, W)];
//添加扫描画面
 _preview =[AVCaptureVideoPreviewLayer layerWithSession:_session];
 _preview.videoGravity =AVLayerVideoGravityResizeAspectFill;
 _preview.frame = CGRectMake(0, 0, ScreenW, ScreenH);//self.view.layer.bounds;
 [self.view.layer insertSublayer:_preview atIndex:0];
 //开始扫描
 [_session startRunning];

//添加扫描动画定时器
[self.outputView addSubview:self.lineImage];
 // Do any additional setup after loading the view from its nib.
 _timer = [NSTimer scheduledTimerWithTimeInterval:2.5f
           target:self
           selector:@selector(lineAction)
           userInfo:nil
           repeats:YES];
}

-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
 NSString *stringValue;
 if ([metadataObjects count] >0){
  //停止扫描
  [_session stopRunning];
  AVMetadataMachineReadableCodeObject * metadataObject = [metadataObjects objectAtIndex:0];
  stringValue = metadataObject.stringValue;//stringValue是扫描拿到的内容，更具内容进行后续工作。
 }
}

- (void)lineAction{
 CGFloat outputW = self.outputView.frame.size.width;
 CGFloat outputH = self.outputView.frame.size.height;
 [UIView animateWithDuration:2.4f animations:^{
  CGRect frame = CGRectMake(0, outputH, outputW, 2);
  self.lineImage.frame = frame;
 } completion:^(BOOL finished) {
  CGRect frame = CGRectMake(0, 0, outputW, 2);
  self.lineImage.frame = frame;
 }];
}