我正在开发QR码阅读器应用程序。 Hier是我的代码:
var captureSession: AVCaptureSession?
var videoPreviewLayer: AVCaptureVideoPreviewLayer?
var qrCodeframeView: UIView?
@IBOutlet weak var CancelButton: UIButton!
@IBOutlet weak var Label: UILabel!
override func viewDidLoad() {
CancelButton.hidden = true
Label.hidden = true
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
@IBAction func ScanMe(sender: AnyObject) {
CancelButton.hidden = false
Label.hidden = false
let captureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
var error: NSError?
let input: AnyObject!
do {
input = try AVCaptureDeviceInput (device: captureDevice)
} catch let error1 as NSError{
error = error1
input = nil
}
if (error != nil){
print ("\(error?.localizedDescription)")
return
}
captureSession = AVCaptureSession()
captureSession?.addInput(input as! AVCaptureInput)
let captureMetadatOutput = AVCaptureMetadataOutput()
captureSession?.addOutput(captureMetadatOutput)
captureMetadatOutput.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())
captureMetadatOutput.metadataObjectTypes = [AVMetadataObjectTypeQRCode]
videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
videoPreviewLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
videoPreviewLayer?.frame = view.layer.bounds
view.layer.addSublayer(videoPreviewLayer!)
captureSession?.startRunning()
view.bringSubviewToFront(Label)
view.bringSubviewToFront(CancelButton)
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!) {
if metadataObjects == nil || metadataObjects.count == 0 {
qrCodeframeView?.frame = CGRectZero
Label.text = "No QR code detected"
return
}
let metadateObj = metadataObjects[0] as! AVMetadataMachineReadableCodeObject
if metadateObj.type == AVMetadataObjectTypeQRCode {
let BarcodeObject = videoPreviewLayer?.transformedMetadataObjectForMetadataObject(metadateObj as AVMetadataMachineReadableCodeObject) as! AVMetadataMachineReadableCodeObject
qrCodeframeView?.frame = BarcodeObject.bounds
if metadateObj.stringValue != nil {
Label.text = metadateObj.stringValue
captureSession?.stopRunning()
}
}
}
@IBAction func Cancel(sender: AnyObject) {
CancelButton.hidden = true
Label.hidden = true
captureSession?.stopRunning()
qrCodeframeView?.removeFromSuperview()
videoPreviewLayer?.removeFromSuperlayer()
}
@IBAction func Open(sender: AnyObject) {
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
var PC : SecondSecondViewController = segue.destinationViewController as! SecondSecondViewController
PC.label1 = Label.text!
}
}
问题是,当我单击取消按钮并返回上一个viewcontroller时,当我重新打开qr代码扫描程序时,我看到最后扫描的代码,显示在Label.text中。您能否帮我清除标签并不显示旧代码,因为这些代码只能使用一次,如果用户看到代码,他们就可以再次使用它们。
答案 0 :(得分:0)
如果您不想添加其他回调:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
var PC : SecondSecondViewController = segue.destinationViewController as! SecondSecondViewController
PC.label1 = Label.text!
Label.text = ""
}
否则当你从SecondSecondViewController
回来并设置Label.text = ""
答案 1 :(得分:0)
只需将其添加到退出QR的位置(按取消):
label.text = ""