相关疑难解决方法(0)

我正在尝试将mi app升级到swift 4,但条形码阅读器无法正常工作.

我已经隔离了条形码阅读器代码,但仍然无法正常工作.相机可以正常工作但不会检测到条形码.

代码在swift 3 iOS 10上运行得很好.

这是完整的代码

import AVFoundation
import UIKit

class ViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
var captureSession: AVCaptureSession!
var previewLayer: AVCaptureVideoPreviewLayer!

override func viewDidLoad() {
    super.viewDidLoad()

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

    let videoCaptureDevice = AVCaptureDevice.default(for: AVMediaType.video)
    let videoInput: AVCaptureDeviceInput

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

    if (captureSession.canAddInput(videoInput)) {
        captureSession.addInput(videoInput)
    } else {
        failed();
        return;
    }

    let metadataOutput = AVCaptureMetadataOutput()

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

        metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
        metadataOutput.metadataObjectTypes = [AVMetadataObject.ObjectType.ean8, AVMetadataObject.ObjectType.ean13, …

我知道有人问过这个问题.但遗憾的是我没有找到答案.

dispatchQueue = dispatch_queue_create("myQueue", NULL);
[captureMetadaOutput setMetadataObjectsDelegate:self queue:dispatchQueue];
//  [captureMetadaOutput setMetadataObjectTypes:[NSArray arrayWithObject:AVMetadataObjectTypeQRCode]];
//  ??????
captureMetadaOutput.metadataObjectTypes = @[AVMetadataObjectTypeQRCode];

我收到Crashlytics的崩溃信息:

[AVCaptureMetadataOutput setMetadataObjectTypes:] - 找不到支持的类型.使用-availableMetadataObjectTypes.