AVFoundation，AVCaptureMetadataOutput截图

Question

我使用AVCaptureMetadataOutput是为了使用iOS QRCode，条形码扫描功能。这样做很好，我通过AVCaptureMetadataOutput委托方法获得了扫描结果。

-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{

但是我不知道如何用我在这个委托中的数据来捕获扫描的qrcode，条形码的图像。

Answer 1

我有captured image，而scanning QRCode是这样的：

1)首先添加AVCaptureStillImageOutput's的属性

@property (strong, nonatomic) AVCaptureStillImageOutput *stillImageOutput;

2)初始化后在AVCaptureSession中添加会话预置

[self.session setSessionPreset:AVCaptureSessionPreset640x480];

3)现在在AVCaptureSession中添加AVCaptureStillImageOutput's作为输出

// Prepare an output for snapshotting
self.stillImageOutput = [AVCaptureStillImageOutput new];
[self.session addOutput:self.stillImageOutput];
self.stillImageOutput.outputSettings = @{AVVideoCodecKey: AVVideoCodecJPEG};

4)在下面添加代码，以便在委托方法captureOutput:didOutputMetadataObjects:fromConnection:connection中捕获扫描图像

 __block UIImage *scannedImg = nil;
// Take an image of the face and pass to CoreImage for detection
AVCaptureConnection *stillConnection = [self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo];
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:stillConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
    if(error) {
        NSLog(@"There was a problem");
        return;
    }

    NSData *jpegData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];

    scannedImg = [UIImage imageWithData:jpegData];
    NSLog(@"scannedImg : %@",scannedImg);
}];

对于参考，使用CodeScanViewController

Thats it @