iOS快速扫描多个条形码

我使用以下代码扫描条形码：

func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {

    var highlightViewRect = CGRectZero

    var barCodeObject : AVMetadataObject!

    var detectionString : String!

    let barCodeTypes = [AVMetadataObjectTypeUPCECode,
        AVMetadataObjectTypeCode39Code,
        AVMetadataObjectTypeCode39Mod43Code,
        AVMetadataObjectTypeEAN13Code,
        AVMetadataObjectTypeEAN8Code,
        AVMetadataObjectTypeCode93Code,
        AVMetadataObjectTypeCode128Code,
        AVMetadataObjectTypePDF417Code,
        AVMetadataObjectTypeQRCode,
        AVMetadataObjectTypeAztecCode
    ]


    // The scanner is capable of capturing multiple 2-dimensional barcodes in one scan.

    for metadata in metadataObjects {
        for barcodeType in barCodeTypes {

            if metadata.type == barcodeType {
                barCodeObject = self.previewLayer.transformedMetadataObjectForMetadataObject(metadata as! AVMetadataMachineReadableCodeObject)

                highlightViewRect = barCodeObject.bounds

                detectionString = (metadata as! AVMetadataMachineReadableCodeObject).stringValue

                let len = detectionString.characters.count
                print("raw=\(detectionString)")
                if len == 25 {
                    detectionString=detectionString.substringWithRange(Range<String.Index>(start: detectionString.startIndex.advancedBy(3), end: detectionString.endIndex.advancedBy(0)))
                } else if len > 22 {
                    detectionString=detectionString.substringWithRange(Range<String.Index>(start: detectionString.startIndex.advancedBy(22), end: detectionString.endIndex.advancedBy(0)))
                }
                print("mod=\(detectionString)")
            }

        }
    }

    self.session.stopRunning()
    sendScan(detectionString)

    self.highlightView.frame = highlightViewRect
    self.view.bringSubviewToFront(self.highlightView)

}

func captureOutput（captureOutput:AVCaptureOutput！，didOutputMetadataObjects metadataObjects:[AnyObject]！，fromConnection连接：AVCaptureConnection！）{
var highlightViewRect=CGRectZero
var barCodeObject:AVMetadataObject！
变量检测字符串：字符串！
让barCodeTypes=[AVMetadataObjectTypeUPCECode，
AVMetadataObjectTypeCode39Code，
AVMetadataObjectTypeCode39Mod43Code，
AVMetadataObjectTypeAn13Code，
AVMetadataObjectTypeAna8Code，
AVMetadataObjectTypeCode93Code，
AVMetadataObjectTypeCode128Code，
AVMetadataObjectTypePDF417代码，
AVMetadataObjectTypeQRCode，
AVMetadataObjectTypeAztecCode
]
//扫描仪能够在一次扫描中捕获多个二维条形码。
用于元数据对象中的元数据{
对于barCodeTypes中的barcodeType{
如果metadata.type==barcodeType{
barCodeObject=self.previewLayer.TransformedMetadataObjectFormMetadataObject（元数据为！AVMetadataMachineReadableCodeObject）
highlightViewRect=barCodeObject.bounds
detectionString=（元数据为！avMetadataMachineAdableCodeObject）。stringValue
设len=detectionString.characters.count
打印（“原始=\（检测字符串）”）
如果len==25{
detectionString=detectionString.substringWithRange（范围（开始：detectionString.startIndex.advancedBy（3），结束：detectionString.endIndex.advancedBy（0）））
}否则，如果len>22{
detectionString=detectionString.substringWithRange（范围（开始：detectionString.startIndex.advancedBy（22），结束：detectionString.endIndex.advancedBy（0）））
}
打印（“mod=\（detectionString）”）
}
}
}
self.session.stopRunning（）
发送扫描（检测字符串）
self.highlightView.frame=highlightView-rect
self.view.bringsubview到前面（self.highlightView）
}

---

看起来它应该从同一次扫描中捕获多个条形码。然而，它只捕获了一个。我肯定我在这里做错了什么，但我不确定是什么。

同时检测的最大数量是4，这个数字仅适用于二维条形码。一维条码识别仅限于一次检测。有关更多信息，请参阅此参考：

运行您的代码（就所提供的范围而言），可以获得多个（2D）检测。请注意，sendScan方法只发送最后检测到的项目

对代码稍作修改：

func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {

    var captures : [String] = []

    for metadata in metadataObjects {

        var detectionString = (metadata as! AVMetadataMachineReadableCodeObject).stringValue


        let len = detectionString.characters.count
        print("raw=\(detectionString)")
        if len == 25 {
            detectionString = detectionString.substringWithRange(Range<String.Index>(start: detectionString.startIndex.advancedBy(3), end: detectionString.endIndex.advancedBy(0)))
        } else if len > 22 {
            detectionString = detectionString.substringWithRange(Range<String.Index>(start: detectionString.startIndex.advancedBy(22), end: detectionString.endIndex.advancedBy(0)))
        }
        print("mod=\(detectionString)")


        captures.append(detectionString)

    }

    print("Captured \(captures.count) barcodes.")

}

raw=www.barcode1.co.za
mod=www.barcode1.co.za
raw=http://www.moxx.in
mod=http://www.moxx.in
raw=http://www.harrowhouse.com/
mod=.com/
raw=Ver1
mod=Ver1
Captured 4 barcodes.