我正在尝试将 mi 应用程序升级到 swift 4,但条形码读取器无法工作。
我已经隔离了条形码读取器代码,但仍然无法工作。相机可以工作,但无法检测到条形码。
该代码在 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, AVMetadataObject.ObjectType.pdf417]
} else {
failed()
return
}
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession);
previewLayer.frame = view.layer.bounds;
previewLayer.videoGravity = AVLayerVideoGravity.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) {
super.viewWillDisappear(animated)
if (captureSession?.isRunning == true) {
captureSession.stopRunning();
}
}
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {
captureSession.stopRunning()
if let metadataObject = metadataObjects.first {
let readableObject = metadataObject as! AVMetadataMachineReadableCodeObject;
AudioServicesPlaySystemSound(SystemSoundID(kSystemSoundID_Vibrate))
found(code: readableObject.stringValue!);
}
dismiss(animated: true)
}
func found(code: String) {
print(code)
}
override var prefersStatusBarHidden: Bool {
return true
}
override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
return .portrait
}
}
我在 iPhone 上使用 iOS 11,已升级至 beta 9。
任何想法?谢谢。
我明白了,但苹果并没有说得那么明显。委托 AVCaptureMetadataOutputObjectsDelegate 的回调函数已重命名,并且参数名称不同!
所以,更换
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!)
to
func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection)
此后,我的视图控制器现在像以前一样扫描二维码。它具有相同的参数,但第一个参数名称不同。更改函数和参数名称并构建/运行。
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