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该问题仅在没有背景 NFC 读取的 iPhone 8 等旧 NFC 设备上重现，但在 iPhone 12、11、X 上一切正常。单击取消（使会话无效）后 - 无法再次启动 NFC 会话. 只有在强制关闭应用程序后才能重新启动。这是打开会话的代码（按钮扫描）

session = NFCNDEFReaderSession(delegate: self, queue: nil, invalidateAfterFirstRead: true)
session?.alertMessage = "Hold your iPhone near the item to scan tag."
session?.begin()

委托方法代码 NFCNDEFReaderSessionDelegate

func readerSession(_ session: NFCNDEFReaderSession, didDetectNDEFs messages: [NFCNDEFMessage]) {
      guard let ndefMessage = messages.first,
            let record = ndefMessage.records.first,
            record.typeNameFormat == .absoluteURI || record.typeNameFormat == .nfcWellKnown,
            let payloadText = String(data: record.payload, encoding: .utf8) else {
                return
        }
        print("scanned NFC info: \(payloadText)")
        self.session = nil
    }
    
    
    func readerSession(_ session: NFCNDEFReaderSession, didInvalidateWithError error: Error) {
        if let readerError = error as? NFCReaderError {
            if (readerError.code != .readerSessionInvalidationErrorFirstNDEFTagRead)
                && (readerError.code != .readerSessionInvalidationErrorUserCanceled) {
                let alertController = UIAlertController(
                    title: "Session is expired.",
                    message: "Please, try again.",//error.localizedDescription,
                    preferredStyle: .alert
                )
                alertController.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
                DispatchQueue.main.async {
                    self.present(alertController, animated: true, completion: nil)
                }
            }
        }
        self.session = nil
    }
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1 回答 1

0

您将不得不重新开始会话。

 @IBAction func beingScanning(){
         guard !session?.isReady else {
           return
         }
// invalidateAfterFirstRead = false
         session = NFCNDEFReaderSession(delegate: self, queue: nil, invalidateAfterFirstRead: false)
         session?.alertMessage = "Hold your iPhone near the item to scan tag."
         session?.begin()
    }

也使用invalidateAfterFirstRead假而不是真。成功阅读后，您可以将其无效。

于 2021-02-14T14:35:27.160 回答