[英]Code for capturing QR Code doesn't seem working well in Xcode8 and Swift3
我正在尝试在Swift3和iOS 10 beta设备中使用AVCaptureMetadataOutputObjectsDelegate
捕获QR码。
但是,当设备的相机实际捕获QR码时,不会调用captureOutput
函数。
有人对此有解决方案吗? 如果是这样,请让我知道如何修复和正常工作。
谢谢,
import UIKit
import AVFoundation
class ViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
override func viewDidLoad() {
super.viewDidLoad()
let mySession: AVCaptureSession! = AVCaptureSession()
let devices = AVCaptureDevice.devices()
var myDevice: AVCaptureDevice!
for device in devices! {
if((device as AnyObject).position == AVCaptureDevicePosition.back){
myDevice = device as! AVCaptureDevice
}
}
let myVideoInput = try! AVCaptureDeviceInput.init(device: myDevice)
if mySession.canAddInput(myVideoInput) {
mySession.addInput(myVideoInput)
}
let myMetadataOutput: AVCaptureMetadataOutput! = AVCaptureMetadataOutput()
if mySession.canAddOutput(myMetadataOutput) {
mySession.addOutput(myMetadataOutput)
myMetadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
myMetadataOutput.metadataObjectTypes = [AVMetadataObjectTypeQRCode]
}
let myVideoLayer = AVCaptureVideoPreviewLayer.init(session: mySession)
myVideoLayer?.frame = self.view.bounds
myVideoLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
self.view.layer.addSublayer(myVideoLayer!)
mySession.startRunning()
}
// MARK: - AVCaptureMetadataOutputObjectsDelegate
// This function is not called despite capturing QR code
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, from connection: AVCaptureConnection!) {
if metadataObjects.count > 0 {
let qrData: AVMetadataMachineReadableCodeObject = metadataObjects[0] as! AVMetadataMachineReadableCodeObject
print("\(qrData.type)")
print("\(qrData.stringValue)")
}
}
}
在Swift 3中实现AVCaptureMetadataOutputObjectsDelegate
的方法标头如下所示:
func captureOutput(_ captureOutput: AVCaptureOutput!,
didOutputMetadataObjects metadataObjects: [Any]!,
from connection: AVCaptureConnection!) {
[AnyObject]
-> [Any]
,我还没有检查代码的其他部分,但是至少您需要解决此问题。
Swift 4中的委托方法
func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) {}
SWIFT 3:就我而言,这段代码解决了这个问题:
旧的错误代码
private func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {
for item in metadataObjects {
if let metadataObject = item as? AVMetadataMachineReadableCodeObject {
if metadataObject.type == AVMetadataObjectTypeQRCode {
print("QR Code: \(metadataObject.stringValue)")
}
}
}
}
正确答案
func captureOutput(_ captureOutput: AVCaptureOutput!,
didOutputMetadataObjects metadataObjects: [Any]!,
from connection: AVCaptureConnection!) {
for item in metadataObjects {
if let metadataObject = item as? AVMetadataMachineReadableCodeObject {
if metadataObject.type == AVMetadataObjectTypeQRCode {
print("QR Code: \(metadataObject.stringValue)")
}
}
}
}
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