iOS利用AVCaptureSession实现二维码扫描 iOS利用AVCaptureSession实现二维码

1 首先使APP获得相机使用权限在plist文件中用source code的方式打开，添加如下代码：

NSCameraUsageDescription cameraDesciption

如果没有使应用获取相机使用权限，则使用过程中会崩溃。
2 判断权限也就是针对是否获得相机使用权限做检验：

[AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) { dispatch_async(dispatch_get_main_queue(), ^{if (granted) { //配置扫描view [self loadScanView]; } else { NSString *title = @"请在iPhone的”设置-隐私-相机“选项中，允许App访问你的相机"; UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:title message:@"" delegate:nil cancelButtonTitle:@"好" otherButtonTitles:nil]; [alertView show]; }}); }];

3 配置扫描view

- (void)loadScanView { //1.初始化捕捉设备（AVCaptureDevice），类型为AVMediaTypeVideo AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; //2.用captureDevice创建输入流 AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:nil]; //3.创建媒体数据输出流 AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init]; //4.实例化捕捉会话 _captureSession = [[AVCaptureSession alloc] init]; //4.1.将输入流添加到会话 [_captureSession addInput:input]; //4.2.将媒体输出流添加到会话中 [_captureSession addOutput:output]; //5.设置代理在主线程里刷新 [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()]; //5.2.设置输出媒体数据类型为QRCode [output setMetadataObjectTypes:[NSArray arrayWithObject:AVMetadataObjectTypeQRCode]]; //6.实例化预览图层 _videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_captureSession]; //7.设置预览图层填充方式 [_videoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill]; //8.设置图层的frame [_videoPreviewLayer setFrame:_viewPreview.layer.bounds]; //9.将图层添加到预览view的图层上 [_viewPreview.layer addSublayer:_videoPreviewLayer]; //10.设置扫描范围 output.rectOfInterest = CGRectMake(0.2f, 0.2f, 0.8f, 0.8f); //10.1.扫描框 _boxView = [[UIView alloc] initWithFrame:CGRectMake(_viewPreview.bounds.size.width * 0.2, _viewPreview.bounds.size.height*0.2, _viewPreview.bounds.size.width - _viewPreview.bounds.size.width * 0.4f, _viewPreview.bounds.size.width - _viewPreview.bounds.size.width * 0.4f)]; _boxView.layer.borderColor = [UIColor redColor].CGColor; _boxView.layer.borderWidth = 1.0; [_viewPreview addSubview:_boxView]; _scanLayer = [[CALayer alloc] init]; _scanLayer.frame = CGRectMake(0, 0, _boxView.bounds.size.width, 1); _scanLayer.backgroundColor = [UIColor blackColor].CGColor; [_boxView.layer addSublayer:_scanLayer]; [self startRunning]; }

这里我们用到rectOfInterest 这个cgrect跟平时用的不一样，在这里用的是比例来表示，也就是利用这个可以设置扫描的方框的范围
4 开始扫描

#pragma mark 开始 - (void)startRunning { if (self.captureSession) { self.isReading = YES; [self.captureSession startRunning]; _timer=[NSTimer scheduledTimerWithTimeInterval:0.2 target:self selector:@selector(moveUpAndDownLine) userInfo:nil repeats: YES]; } }

5 扫描线移动

- (void)moveUpAndDownLine { CGRect frame = self.scanLayer.frame; if (_boxView.frame.size.height < self.scanLayer.frame.origin.y) { frame.origin.y = 0; self.scanLayer.frame = frame; } else { frame.origin.y += 5; [UIView animateWithDuration:0.2 animations:^{ self.scanLayer.frame = frame; }]; } }

6 AVCaptureMetadataOutputObjectsDelegate 【iOS利用AVCaptureSession实现二维码扫描】这个是里面用到的最重要的方法，在这个代理方法里我们可以获得扫描二维码解析出来的数据，然后在里面进行操作

#pragma mark - AVCaptureMetadataOutputObjectsDelegate - (void)captureOutput:(AVCaptureOutput *)output didOutputMetadataObjects:(NSArray<__kindof AVMetadataObject *> *)metadataObjects fromConnection:(AVCaptureConnection *)connection { //判断是否有数据 if (!_isReading) { return; } if (metadataObjects.count > 0) { _isReading = NO; AVMetadataMachineReadableCodeObject *metadataObject = metadataObjects[0]; NSString *result = metadataObject.stringValue; if (self.resultBlock) { self.resultBlock(result?:@""); } [self.navigationController popViewControllerAnimated:NO]; } }

7 退出时记得关闭

#pragma mark 结束 - (void)stopRunning { if ([_timer isValid]) { [_timer invalidate]; _timer = nil ; } [self.captureSession stopRunning]; [_scanLayer removeFromSuperlayer]; [_videoPreviewLayer removeFromSuperlayer]; }

代码地址：https://github.com/irembeu/ScanSignDemo.git