iOS利用AVCaptureSession实现二维码扫描

LeonardValentina 发布于6月前 阅读47次
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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:

<key>
 NSCameraUsageDescription
</key>
    
<string>
 cameraDesciption
</string>

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

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];
}

作者:劉光軍_Shine

链接:https://www.jianshu.com/p/60effc200c95

查看原文: iOS利用AVCaptureSession实现二维码扫描

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