二维码扫描主要使用苹果自带的AVFoundation框架

设置二维码周边黑框

    CGFloat width = 70 * UISCALE;
    CGFloat topHeight = 160 * UISCALE;
    CGFloat bottomHeight = SCREEN_HEIGHT - 360 * UISCALE;
    
    self.imgView.frame = CGRectMake(width, topHeight, SCREEN_WIDTH - width * 2, SCREEN_HEIGHT - topHeight - bottomHeight);
    
    //最上部view
    CGFloat alpha = 0.6;
    CGFloat withWhite = 0.3;
    UIView* upView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, topHeight)];
    upView.backgroundColor = [UIColor colorWithWhite:withWhite alpha:alpha];
    [self.view addSubview:upView];
    
    //左侧的view
    UIView * cLeftView = [[UIView alloc] initWithFrame:CGRectMake(0, topHeight, width, 200 * UISCALE)];
    cLeftView.backgroundColor = [UIColor colorWithWhite:withWhite alpha:alpha];
    [self.view addSubview:cLeftView];
    
    //右侧的view
    UIView *rightView = [[UIView alloc] initWithFrame:CGRectMake(SCREEN_WIDTH - width, topHeight, width, 200 * UISCALE)];
    rightView.backgroundColor = [UIColor colorWithWhite:withWhite alpha:alpha];
    [self.view addSubview:rightView];
    
    //底部view
    UIView * downView = [[UIView alloc] initWithFrame:CGRectMake(0, 360 * UISCALE, SCREEN_WIDTH, bottomHeight)];
    downView.backgroundColor = [UIColor colorWithWhite:withWhite alpha:alpha];
    [self.view addSubview:downView];
    
    //用于说明的label
    UILabel * labIntroudction= [[UILabel alloc] init];
    labIntroudction.frame = CGRectMake(0, 10 * UISCALE, SCREEN_WIDTH, 30 * UISCALE);
    labIntroudction.textAlignment = NSTextAlignmentCenter;
    labIntroudction.textColor = [UIColor colorWithWhite:0.9 alpha:0.9];
    labIntroudction.text = @"对准二维码，即可自动扫描";
    labIntroudction.font = FontWithSize(15);
    [downView addSubview:labIntroudction];

设置二维码扫描layer

    // 1、 获取摄像设备
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    // 2、 创建输入流
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
    // 3、 创建输出流
    AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
    // 4、设置代理 在主线程里刷新
    [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    // 设置扫描范围(每一个取值0～1，以屏幕右上角为坐标原点)（微信并没有设置， 整个View都是扫描区域）
    [[NSNotificationCenter defaultCenter] addObserverForName:AVCaptureInputPortFormatDescriptionDidChangeNotification
                                                      object:nil
                                                       queue:[NSOperationQueue currentQueue]
                                                  usingBlock: ^(NSNotification *_Nonnull note) {
                                                      output.rectOfInterest = [self.previewLayer metadataOutputRectOfInterestForRect:self.imgView.frame];
                                                  }];
    // 5、 初始化链接对象（会话对象）
    self.session = [[AVCaptureSession alloc] init];
    // 高质量采集率
    [self.session setSessionPreset:AVCaptureSessionPresetHigh];
    // 5.1 添加会话输入
    if ([self.session canAddInput:input]) {
        [self.session addInput:input];
    }
    // 5.2 添加会话输出
    if ([self.session canAddOutput:output]) {
        [self.session addOutput:output];
        //设置扫码支持的编码格式(如下设置条形码和二维码兼容)
        NSMutableArray *array = [[NSMutableArray alloc] init];
        if ([output.availableMetadataObjectTypes containsObject:AVMetadataObjectTypeQRCode]) {
            [array addObject:AVMetadataObjectTypeQRCode];
        }
        if ([output.availableMetadataObjectTypes containsObject:AVMetadataObjectTypeEAN13Code]) {
            [array addObject:AVMetadataObjectTypeEAN13Code];
        }
        if ([output.availableMetadataObjectTypes containsObject:AVMetadataObjectTypeEAN8Code]) {
            [array addObject:AVMetadataObjectTypeEAN8Code];
        }
        if ([output.availableMetadataObjectTypes containsObject:AVMetadataObjectTypeCode128Code]) {
            [array addObject:AVMetadataObjectTypeCode128Code];
        }
        output.metadataObjectTypes = array;
    }
    // 7、实例化预览图层, 传递_session是为了告诉图层将来显示什么内容
    self.previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:_session];
    self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    self.previewLayer.frame = [UIScreen mainScreen].bounds;
    // 8、将图层插入当前视图
    [self.view.layer insertSublayer:self.previewLayer atIndex:0];
    // 9、启动会话
    [self.session startRunning];

AVCaptureMetadataOutputObjectsDelegate

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
    // 1、设置界面显示扫描结果
    if (metadataObjects.count > 0) {
        AVMetadataMachineReadableCodeObject *obj = metadataObjects[0];
        NSLog(@"%@", obj.stringValue);
        PCBaseWebViewController *webView = [[PCBaseWebViewController alloc] init];
        webView.url = [NSURL URLWithString:obj.stringValue];
        [self.navigationController pushViewController:webView animated:YES];
    }
    // 会频繁的扫描，调用代理方法
    // 2、如果扫描完成，停止会话
    [self.session stopRunning];
    // 3、删除预览图层
    [self.previewLayer removeFromSuperlayer];
}