如何通過條形碼代碼將數據輸入到CoreData中？

Question

你好，我想輸入代碼到核心數據表中，通過掃描條形碼來獲得這段代碼，以及如何在將代碼插入到數據庫之前使用匹配的數組代碼進行編碼，然後在應用程序運行時需要一個條件第二次審查現有數據庫中的代碼

條形碼代碼

func barcodefunc(){ 
     // Get an instance of the AVCaptureDevice class to initialize a device object and provide the video 
     // as the media type parameter. 
     let captureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo) 

     // Get an instance of the AVCaptureDeviceInput class using the previous device object. 
     var error:NSError? 
     let input: AnyObject! = AVCaptureDeviceInput.deviceInputWithDevice(captureDevice, error: &error) 

     if (error != nil) { 
      // If any error occurs, simply log the description of it and don't continue any more. 
      println("\(error?.localizedDescription)") 
      return 
     } 

     // Initialize the captureSession object. 
     captureSession = AVCaptureSession() 
     // Set the input device on the capture session. 
     captureSession?.addInput(input as AVCaptureInput) 

     // Initialize a AVCaptureMetadataOutput object and set it as the output device to the capture session. 
     let captureMetadataOutput = AVCaptureMetadataOutput() 
     captureSession?.addOutput(captureMetadataOutput) 

     // Set delegate and use the default dispatch queue to execute the call back 
     captureMetadataOutput.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue()) 
     captureMetadataOutput.metadataObjectTypes = supportedBarCodes 

     // Initialize the video preview layer and add it as a sublayer to the viewPreview view's layer. 
     videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession) 
     videoPreviewLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill 
     videoPreviewLayer?.frame = view.layer.bounds 
     view.layer.addSublayer(videoPreviewLayer) 



     // Move the message label to the top view 
     view.bringSubviewToFront(meseg) 

     // Initialize QR Code Frame to highlight the QR code 
     qrCodeFrameView = UIView() 
     qrCodeFrameView?.layer.borderColor = UIColor.greenColor().CGColor 
     qrCodeFrameView?.layer.borderWidth = 2 
     view.addSubview(qrCodeFrameView!) 
     view.bringSubviewToFront(qrCodeFrameView!) 
    } 

    func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection 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 = CGRectZero 
      meseg.text = "No QR code is detected" 
      return 
     } 

     // Get the metadata object. 
     let metadataObj = metadataObjects[0] as AVMetadataMachineReadableCodeObject 

     // Here we use filter method to check if the type of metadataObj is supported 
     // Instead of hardcoding the AVMetadataObjectTypeQRCode, we check if the type 
     // can be found in the array of supported bar codes. 
     if supportedBarCodes.filter({ $0 == metadataObj.type }).count > 0 { 
      // If the found metadata is equal to the QR code metadata then update the status label's text and set the bounds 
      let barCodeObject = videoPreviewLayer?.transformedMetadataObjectForMetadataObject(metadataObj as AVMetadataMachineReadableCodeObject) as AVMetadataMachineReadableCodeObject 
      qrCodeFrameView?.frame = barCodeObject.bounds 

      if metadataObj.stringValue != nil { 
       meseg.text = metadataObj.stringValue 
      } 
     } 
    } 

此coredata代碼

let entityDescripition = NSEntityDescription.entityForName("Usercode", inManagedObjectContext: managedObjectContext!) 
     let task = Usercode(entity: entityDescripition!, insertIntoManagedObjectContext: managedObjectContext) 
     code?.the_code = "ali" 
     managedObjectContext?.save(nil) 

Answer 1

下面是一些示例代碼。首先，你需要在AppDelegate中設置你的核心數據棧你做到了嗎？如果是這樣，這裏是保存到Core Data的代碼。

let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate 
let managedContext = appDelegate.managedObjectContext! 
let entity = NSEntityDescription.entityForName("Usercode",inManagedObjectContext: managedContext) 
let task = Usercode(entity: entity!, insertIntoManagedObjectContext: managedContext) 
task.the_code = "ali" 

var error: NSError? 
if !managedContext.save(&error) { 
println("Could not save \(error), \(error?.userInfo)") 
}