iOS CoreNFC - 类“NFTechnologyEvent”未加载或不存在答案

【问题标题】：iOS CoreNFC - class "NFTechnologyEvent" not loaded or does not existiOS CoreNFC - 类“NFTechnologyEvent”未加载或不存在
【发布时间】：2017-12-13 17:21:14
【问题描述】：

我在尝试使用 iPhone 7 Plus 读取 NFC 标签时遇到此错误

2017-12-13 14:03:01.522137-0300 nfc[279:9534] [general] 连接到名为 com.apple.nfcd.service.corenfc 的服务：在解码收到的消息时捕获异常，丢弃传入的消息。

异常：解码参数 0 时出现异常（调用#2）：

异常：decodeObjectForKey：类“NFTechnologyEvent”未加载或不存在

我已设置适当的权利 (Near Field Communication Tag Reading) 和 Privacy - NFC Scan Usage Description。

要重现它，只需启动一个新的单视图项目并将默认的 ViewController 替换为：

import UIKit
import CoreNFC

class ViewController: UIViewController, NFCNDEFReaderSessionDelegate {
    // Reference the NFC session
    private var nfcSession: NFCNDEFReaderSession!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        self.startScanning()
    }

    func startScanning() {
        // Create the NFC Reader Session when the app starts
        self.nfcSession = NFCNDEFReaderSession(delegate: self, queue: nil, invalidateAfterFirstRead: false)

        // A custom description that helps users understand how they can use NFC reader mode in your app.
        self.nfcSession?.alertMessage = "Macri Gato"

        self.nfcSession?.begin()
    }

    // Called when the reader-session expired, you invalidated the dialog or accessed an invalidated session
    public func readerSession(_ session: NFCNDEFReaderSession, didInvalidateWithError error: Error) {
        print("NFC-Session invalidated: \(error.localizedDescription)")

        print("==========================")

        self.startScanning()
    }

    // Called when a new set of NDEF messages is found
    public func readerSession(_ session: NFCNDEFReaderSession, didDetectNDEFs messages: [NFCNDEFMessage]) {
        print("New NFC Messages (\(messages.count)) detected:")
        print(messages)
    }
}

【问题讨论】：

标签： ios swift core-nfc

【解决方案1】：

在开始 nfcSession 之前，您必须检查 NFCNDEFReaderSession.readingAvailable true 才能继续 session.begin() 方法。

还要确保将“隐私 - NFC 扫描使用说明”添加到 Info.plist

@IBAction func beginScanning(_ sender: Any) {
guard NFCNDEFReaderSession.readingAvailable else {
    let alertController = UIAlertController(
        title: "Scanning Not Supported",
        message: "This device doesn't support tag scanning.",
        preferredStyle: .alert
    )
    alertController.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
    self.present(alertController, animated: true, completion: nil)
    return
}

session = NFCNDEFReaderSession(delegate: self, queue: nil, invalidateAfterFirstRead: false)
session?.alertMessage = "Hold your iPhone near the item to learn more about it."
session?.begin()

}

【讨论】：