Question

我有这个功能

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {

    // Check if the metadataObjects array is not nil and it contains at least one object.
    if metadataObjects == nil || metadataObjects.count == 0 {
        qrCodeFrameView?.frame = CGRect.zero
        messageLabel.text = "No QR/barcode is detected"
        return
    }
    //Get metadata object
    let metadataObj = metadataObjects[0] as! AVMetadataMachineReadableCodeObject

    if supportedCodeTypes.contains(metadataObj.type) {
        //if the found metadata is equal to the QR code metadata then update the status label's text and set the the bounds
        let barCodeObject = videoPreviewLayer?.transformedMetadataObject(for: metadataObj)
        qrCodeFrameView?.frame = barCodeObject!.bounds

        if metadataObj.stringValue != nil {
            messageLabel.text = metadataObj.stringValue
            //Searches firebase for existing barcode
            }
            let itemToSearchFor = metadataObj.stringValue
            let itemID = metadataObj.stringValue
            guard let Description = productDescriptionTextField.text,
            let price = priceTextField.text,
            let location = productLocationTextField.text
            else{
                print("Fill basic product information")
                return
             }
            let ref = FIRDatabase.database().reference(fromURL: "")
            // creating an  item child node
            let values = ["Item Description": Description, "Image": price, "Location": location, "Price": price ]

            let items = ref.child("Items").child(itemID!)
            items.updateChildValues(values, withCompletionBlock: { (err, ref) in
                if err != nil {
                    print(err)
                    return
                } })
             FIRDatabase.database().reference().child("Items").child(itemToSearchFor!).observeSingleEvent(of: .value, with:{(snap) in

                    print(snap)

                        })

    }}

如何从上面的函数中获取“itemID”的值，并在下面的函数中使用它。我试图将函数captureOuput嵌套在函数enterNewProduct中，但它无法正常工作。

  func enterNewProduct() {
  // This is my attempt to nest the function captureOutput inside function enterNewProduct but its not working. 

//        func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!){
    return itemID
    } 


    guard let Description = self.productDescriptionTextField.text,
        let price = self.priceTextField.text,
        let location = self.productLocationTextField.text
        else{
            print("Fill basic product information")
            return
    }
    let ref = FIRDatabase.database().reference(fromURL: " /")
    // creating an  item child node
    let values = ["Item Description": Description, "Image": price, "Location": location, "Price": price ]

    let items = ref.child("Items").child(itemID)
    items.updateChildValues(values, withCompletionBlock: { (err, ref) in
        if err != nil {
            print(err)
            return
        }
    })

我之所以考虑将来自captureOutput的值嵌套或导入到enterNewProduct中的原因是因为我需要在enterNewProduct中使用itemID（已在captureOutput中定义），但它在enterNewProduct中被标记为未解析的标识符。我已经坚持了很长时间。请让我知道如何解决这个问题。

Answer 1

尝试在任何函数之外的Class中声明itemId变量。这将使变量可用于类中的任何函数。

class MainViewController: UIViewController {

 var itemId: String! = String()


 func captureOutput() {

      print(self.itemId)
     //will print whatever the current string value of itemId is

 }


 func enterNewProduct() {

     print(self.itemId)
     //will print whatever the current string value of itemId is

 }



 func otherFunctions() {

     print(self.itemId)
     //will print whatever the current string value of itemId is

 }


}

我如何从一个函数中获取值并在swift中的另一个函数中使用它

1 个答案: