Question

我正在重写我的代码，但它一直在写这个错误，我真的不知道如何修复它。

它说＆＃34;使用未解析的标识符＆＃39;输入＆＃39;＆＃34;在这段代码：

if input != nil {
            session.addInput(input)
        }
        else {
            print(error)
        }

完整代码：

import UIKit
import AVFoundation


class ViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {

    let session         : AVCaptureSession = AVCaptureSession()
    var previewLayer    : AVCaptureVideoPreviewLayer!
    var highlightView   : UIView = UIView()

    override func viewDidLoad() {
        super.viewDidLoad()

        // Allow the view to resize freely
        self.highlightView.autoresizingMask =   [
            .FlexibleTopMargin,
            .FlexibleBottomMargin,
            .FlexibleLeftMargin,
            .FlexibleRightMargin]

        // Select the color you want for the completed scan reticle
        self.highlightView.layer.borderColor = UIColor.greenColor().CGColor
        self.highlightView.layer.borderWidth = 3

        // Add it to our controller's view as a subview.
        self.view.addSubview(self.highlightView)


        // For the sake of discussion this is the camera
        let device = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)

        // Create a nilable NSError to hand off to the next method.
        // Make sure to use the "var" keyword and not "let"
        var error : NSError? = nil


        do {
            let captureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
            _ = try AVCaptureDeviceInput(device: captureDevice)
            // Do the rest of your work...
        } catch let error as NSError {
            // Handle any errors
            print(error)
        }

        // If our input is not nil then add it to the session, otherwise we're kind of done!
        if input != nil {
            session.addInput(input)
        }
        else {
            // This is fine for a demo, do something real with this in your app. :)
            print(error)
        }

        let output = AVCaptureMetadataOutput()
        output.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())
        session.addOutput(output)
        output.metadataObjectTypes = output.availableMetadataObjectTypes


        previewLayer = AVCaptureVideoPreviewLayer(layer: session) as AVCaptureVideoPreviewLayer
        previewLayer.frame = self.view.bounds
        previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
        self.view.layer.addSublayer(previewLayer)

        // Start the scanner. You'll have to end it yourself later.
        session.startRunning()

    }

    // This is called when we find a known barcode type with the camera.
    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

                    self.session.stopRunning()
                    break
                }

            }
        }

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

    }


}

如果有人能帮助我，我会很高兴。

Answer 1

编译器是完全正确的。在您使用它的范围内没有定义变量或常量input。

修复：定义一个与类型相匹配的名为input的变量。

编辑：你可以扔掉几行的类型匹配，在这里：

            _ = try AVCaptureDeviceInput(device: captureDevice)

Read up on error handling in swift。特别是，当来自Obj-C的cp代码时：）

使用未解析的标识符＆＃39;输入＆＃39;

1 个答案: