效果图

WechatIMG1.jpeg

核心代码

初始化AVCaptureSession

- (void)initAVCaptureWithView:(UIView *)parentView {
    
    _device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    
    _input = [AVCaptureDeviceInput deviceInputWithDevice:_device error:nil];
    
    _output = [[AVCaptureMetadataOutput alloc] init];
    [_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    
    _session = [[AVCaptureSession alloc] init];
    _session.sessionPreset = (_screenRect.size.height < 500) ? AVCaptureSessionPreset640x480 : AVCaptureSessionPresetHigh;
    
    if ([_session canAddInput:_input]) {
        [_session addInput:_input];
    }
    if ([_session canAddOutput:_output]) {
        [_session addOutput:_output];
    }
    
    _output.metadataObjectTypes = @[AVMetadataObjectTypeEAN13Code,
                                    AVMetadataObjectTypeEAN8Code,
                                    AVMetadataObjectTypeCode128Code,
                                    AVMetadataObjectTypeQRCode];

    CGSize screenSize = _screenRect.size;
    CGRect screenDrawRect = CGRectMake(0, 0, screenSize.width, screenSize.height);
    
    _scanRect = CGRectMake((screenDrawRect.size.width - _transparentAreaSize.width) / 2,
                           (screenDrawRect.size.height - _transparentAreaSize.height) / 2,
                           _transparentAreaSize.width,
                           _transparentAreaSize.height);
    
    _output.rectOfInterest = CGRectMake(_scanRect.origin.y / screenSize.height,
                                        _scanRect.origin.x / screenSize.width,
                                        _scanRect.size.height / screenSize.height,
                                        _scanRect.size.width / screenSize.width);
    
    _previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:_session];
    _previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    [_previewLayer setFrame:_screenRect];
    [parentView.layer insertSublayer:_previewLayer atIndex:0];
    
    [_session startRunning];
}

获取结果

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects
       fromConnection:(AVCaptureConnection *)connection {
    
    if (metadataObjects.count > 0) {
        [self.scanLineTimer setFireDate:[NSDate distantFuture]];
        [self.session stopRunning];
        
        AVMetadataMachineReadableCodeObject *obj = metadataObjects[0];
        if ([self.delegate respondsToSelector:@selector(didFinshedScanningQRCode:)]) {
            [self.delegate didFinshedScanningQRCode:[obj stringValue]];
        }
    }
}