iOS扫描二维码(系统方法)

步骤如下：

1.导入AVFoundation框架，引入<AVFoundation/AVFoundation.h>

2.设置一个用于显示扫描的view

3.实例化AVCaptureSession、AVCaptureVideoPreviewLayer

@property (weak, nonatomic) IBOutlet UIView *viewPreView;
//捕捉会话
@property (nonatomic, strong) AVCaptureSession *captureSession;
//展示layer
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *videoPreviewLayer;

 _captureSession = nil;
  [self startReading];

开始扫描

- (BOOL)startReading {
    NSError *error;

    //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:&error];
    if (!input) {
        NSLog(@"%@", [error localizedDescription]);
        return NO;
    }

    //3.创建媒体数据输出流
    AVCaptureMetadataOutput *captureMetadataOutput = [[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:captureMetadataOutput];

    //5.创建串行队列，并加媒体输出流添加到队列当中
    dispatch_queue_t dispatchQueue;
    dispatchQueue = dispatch_queue_create("myQueue", NULL);
    //5.1.设置代理
    [captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatchQueue];

    //5.2.设置输出媒体数据类型为QRCode
    [captureMetadataOutput 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
    captureMetadataOutput.rectOfInterest = CGRectMake(0.2f, 0.2f, 0.8f, 0.8f);

    //11.开始扫描
    [_captureSession startRunning];

    return YES;
}

AVCaptureMetadataOutputObjectsDelegate

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
    NSString * stringValue;
    //判断是否有数据
    if (metadataObjects != nil && [metadataObjects count] > 0) {
        AVMetadataMachineReadableCodeObject *metadataObj = [metadataObjects objectAtIndex:0];
        stringValue = metadataObj.stringValue;
    }
    NSLog(@"%@",stringValue);
    [_captureSession stopRunning];
}

　　

来源: http://www.cnblogs.com/spaceID/p/4994443.html