需要导入的库库

AVFoundation/AVFoundation.h

开始创建代码

1. 全局变量设置

   @property (strong,nonatomic)AVCaptureDevice *device;//摄像头
   @property (strong,nonatomic)AVCaptureDeviceInput *input;//输入对象
   @property (strong,nonatomic)AVCaptureMetadataOutput *output;//输入对象
   @property (strong,nonatomic)AVCaptureSession *session;//会话器
   @property (strong,nonatomic)AVCaptureVideoPreviewLayer *preview;//layer层承载控件

2. 需要遵守的代理

   AVCaptureMetadataOutputObjectsDelegate

3. 初始化扫描器与开启扫描

   // 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];
   [_session addInput:self.input];
   [_session addOutput:self.output];

   
   // 条码类型 AVMetadataObjectTypeQRCode
   _output.metadataObjectTypes =@[AVMetadataObjectTypeQRCode];

   
   // Preview
   _preview =[AVCaptureVideoPreviewLayer layerWithSession:self.session];
   _preview.videoGravity = AVLayerVideoGravityResizeAspectFill;
   _preview.frame =CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT - 64);
   [self.view.layer insertSublayer:self.preview atIndex:0];
   // 开启扫描
   [_session startRunning];

扫描结果的代理方法

  #pragma mark AVCaptureMetadataOutputObjectsDelegate
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{

    NSString *stringValue;

    if ([metadataObjects count] >0)
    {
        AVMetadataMachineReadableCodeObject * metadataObject = [metadataObjects objectAtIndex:0];
        stringValue = metadataObject.stringValue;
    }

    [_session stopRunning];
}