的Xcode 9 /雨燕4 AVCaptureMetadataOutput setMetadataObjectTypes使用availableMetadataObjectTypes

Question

似乎有很多相似的問題，我所經歷：

AVmetadata changes with swift 4 xcode 9

AVCaptureMetadataOutput setMetadataObjectTypes unsupported type found

而且還有一個蘋果的錯誤與交易AVFoundation：

https://forums.developer.apple.com/thread/86810#259270

但這些似乎都不是我的答案。
我有在swift 3中運行得很好的代碼，但只會在swift 4中出錯。使用上述鏈接中的解決方案根本沒有任何變化。

代碼：

import UIKit 
import AVFoundation 

class BarCodeScanViewController: UIViewController,  AVCaptureMetadataOutputObjectsDelegate { 
weak var delegate: FlowControllerDelegate? 

var captureSession: AVCaptureSession = AVCaptureSession() 
var previewLayer: AVCaptureVideoPreviewLayer = AVCaptureVideoPreviewLayer() 


override func viewDidLoad() { 
    super.viewDidLoad() 

    view.backgroundColor = UIColor.black 
    captureSession = AVCaptureSession() 

    guard let videoCaptureDevice = AVCaptureDevice.default(for: .video) else { return } 
    let videoInput: AVCaptureDeviceInput 

    do { 
     videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice) 
    } catch { 
     return 
    } 

    if (captureSession.canAddInput(videoInput)) { 
     captureSession.canAddInput(videoInput) 
    } else { 
     failed() 

     return 
    } 

    // let captureMetadataOutput = AVCaptureMetadataOutput() 
    let metadataOutput = AVCaptureMetadataOutput() 

    if captureSession.canAddOutput(metadataOutput) { 
     captureSession.addOutput(metadataOutput) 

     // Check status of camera permissions 
     metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main) 
//   metadataOutput.metadataObjectTypes = [AVMetadataObject.ObjectType.upce] 
     metadataOutput.metadataObjectTypes = [.ean8, .ean13, .pdf417, .upce] 
    } else { 
     failed() 

     return 
    } 

    previewLayer = AVCaptureVideoPreviewLayer(session: captureSession) 
    previewLayer.frame = view.layer.bounds 
    previewLayer.videoGravity = .resizeAspectFill 
    view.layer.addSublayer(previewLayer) 

    captureSession.startRunning() 
} 

func failed() { 
    let ac = UIAlertController(title: "Scanning not supported", message: "Your device does not support scanning a code from an item. Please use a device with a camera.", preferredStyle: .alert) 
    ac.addAction(UIAlertAction(title: "OK", style: .default)) 

    present(ac, animated: true) 

//  captureSession = nil 
} 

override func viewWillAppear(_ animated: Bool) { 
    super.viewWillAppear(animated) 

    if(captureSession.isRunning == false) { 
     captureSession.startRunning() 
    } 
} 

override func viewWillDisappear(_ animated: Bool) { 
    if captureSession.isRunning == true { 
     captureSession.stopRunning() 
    } 

    super.viewWillDisappear(animated) 
} 

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

    if let metatdataObject = metadataObjects.first { 
     guard let readableObject = metatdataObject as? AVMetadataMachineReadableCodeObject else { return } 
     guard let stringValue = readableObject.stringValue else { return } 
     AudioServicesPlaySystemSound(SystemSoundID(kSystemSoundID_Vibrate)) 
     found(code: stringValue) 
    } 

    dismiss(animated: true) 
} 

func found(code: String) { 
    print(code) 
} 

override var prefersStatusBarHidden: Bool { 
    return true 
} 

override var supportedInterfaceOrientations: UIInterfaceOrientationMask  { 
    return .portrait 
} 
} 

當我在Xcode中創建8這個代碼，並迅速3，它工作正常。當我在Xcode中運行它，在添加媒體類型9個迅速4IT崩潰：

metadataOutput.metadataObjectTypes = [.ean8, .ean13, .pdf417, .upce] 

在這兩種情況下，我建立到沒有公測就可以了以前在iOS設備11。

我試過了「__」，看看它是否是上面提到的Apple bug。 如果我將代碼註釋掉，但代碼沒有捕獲。

蘋果介紹的還有其他一些bug嗎？還有誰有相同的問題嗎？

任何幫助，將不勝感激。

感謝

Answer 1

更多信息透明度：

Leevi格雷厄姆是正確的，以及它是真的，蘋果改變堆棧無適當證件。這導致它看起來像有一個錯誤。

Barcode on swift 4

明確的意見，幫助我：

委託回調已經從：更改

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

到

func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) 

不過，我有真正的問題是你不再設置多種類型來獲得你的metadataObjectTypes。現在，您只需設置爲所有可用類型：

metadataOutput.metadataObjectTypes = 
metadataOutput.availableMetadataObjectTypes 

所以......

這一點，實際上是一個API的問題。提交了幾個雷達問題。但是蘋果善意地改變了他們的AVFoundation文件來解決這個問題。