ios - I have stopped captureSession but Scanner is yet working. How to resolve this bug? - 


func scan(){     capturesession = avcapturesession()      let videoinput: avcapturedeviceinput     let videocapturedevice = avcapturedevice.defaultdevice(withmediatype: avmediatypevideo)     let metadataoutput = avcapturemetadataoutput()      {         videoinput = try avcapturedeviceinput(device: videocapturedevice)     } catch {         return     }      if (capturesession.canaddinput(videoinput)) {         capturesession.addinput(videoinput)     } else {         failed()         return     }      if (capturesession.canaddoutput(metadataoutput)) {         capturesession.addoutput(metadataoutput)          metadataoutput.setmetadataobjectsdelegate(self, queue: dispatchqueue.main)         metadataoutput.metadataobjecttypes = [avmetadataobjecttypeean8code, avmetadataobjecttypeean13code, avmetadataobjecttypepdf417code, avmetadataobjecttypecode128code, avmetadataobjecttypeitf14code, avmetadataobjecttypecode39code]     } else {         failed()         return     }     var caplayer = self.previewlayer     caplayer = avcapturevideopreviewlayer(session: capturesession);     caplayer?.videogravity = avlayervideogravityresizeaspectfill     caplayer?.frame = self.cameraview.layer.bounds     self.cameraview.layer.addsublayer(caplayer!)     capturesession.startrunning() }  func failed() {     let ac = uialertcontroller(title: "scanning not supported", message: "your device not support scanning code item. please use device camera.", preferredstyle: .alert)     ac.addaction(uialertaction(title: "ok", style: .default, handler: nil))     present(ac, animated: true, completion: nil)     capturesession = nil } func captureoutput(_ captureoutput: avcaptureoutput!, didoutputmetadataobjects metadataobjects: [any]!, connection: avcaptureconnection!) {     capturesession.stoprunning()      if let metadataobject: anyobject = metadataobjects.first anyobject? {         let readableobject = metadataobject as! avmetadatamachinereadablecodeobject;         audioservicesplaysystemsound(systemsoundid(ksystemsoundid_vibrate))         foundcode(readableobject.stringvalue)     }     if (capturesession?.isrunning == true) {         capturesession.stoprunning()         capturesession = nil     }      dismiss(animated: true, completion: nil) } func foundcode(_ code: string) {     capturesession.stoprunning()     storeid = (userdefaults.standard.value(forkey: defaultskey.storeid.rawvalue) as? int)!     scannedcode = ("\(code)")     if (capturesession?.isrunning == true) {         capturesession.stoprunning()         capturesession = nil     }     apicall() }

structure of app: triggering scan on click of button after successful api call. have stopped capture session once barcode found continuously scanning , sendung multiple api calls.

suggest how stop camera scanning without being triggered.

i guess @ point still stops , had same issue it. problem capture session uses queue, , when manages scan something, still able scan several times, until code stops it. why receive several delegate callbacks.

you can have 2 options here:

  1. make delegate nil when first receive callback , set again when want start.(though not sure work)
  2. as did... introduce bool flag filter unwanted callbacks in delegate.

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