iOS平台下如何向ISO 14443-4格式NFC标签发送自定义指令？

要发送30 4F（读取第79块）指令到ISO 14443-4标签，核心是将检测到的标签转换为NFCISO14443Tag类型后调用sendCommand方法，以下是完整实现步骤和代码：

1. 基础配置 #

确保项目已开启NFC权限：

• 在Info.plist中添加NFCReaderUsageDescription权限描述
• 勾选项目Capabilities中的Near Field Communication Tag Reading

2. 核心代码实现 #

import CoreNFC

class NFCReaderViewController: UIViewController, NFCTagReaderSessionDelegate {
    private var nfcSession: NFCTagReaderSession?

    // 启动NFC会话
    func startNFCSession() {
        guard NFCTagReaderSession.readingAvailable else {
            print("设备不支持NFC读取")
            return
        }
        nfcSession = NFCTagReaderSession(pollingOption: .iso14443, delegate: self, queue: nil)
        nfcSession?.begin()
    }

    // 检测到标签时触发
    func tagReaderSession(_ session: NFCTagReaderSession, didDetect tags: [NFCTag]) {
        guard let tag = tags.first else {
            session.invalidate(errorMessage: "未检测到有效标签")
            return
        }

        // 连接标签
        session.connect(to: tag) { [weak self] error in
            guard let self = self else { return }
            if let error = error {
                session.invalidate(errorMessage: "连接标签失败：\(error.localizedDescription)")
                return
            }

            // 将标签转换为ISO14443类型
            guard let isoTag = tag as? NFCISO14443Tag else {
                session.invalidate(errorMessage: "标签不符合ISO 14443-4标准")
                return
            }

            // 将十六进制指令30 4F转为Data
            let commandData = Data(hexString: "304F")

            // 发送指令
            isoTag.sendCommand(commandPacket: commandData) { responseData, error in
                if let error = error {
                    session.invalidate(errorMessage: "发送指令失败：\(error.localizedDescription)")
                    return
                }

                // 处理响应数据（示例：转为十六进制字符串）
                if let response = responseData {
                    let hexResponse = response.hexString
                    print("读取到的响应：\(hexResponse)")
                    session.invalidate()
                }
            }
        }
    }

    // NFC会话无效时触发
    func tagReaderSession(_ session: NFCTagReaderSession, didInvalidateWithError error: Error) {
        print("NFC会话无效：\(error.localizedDescription)")
        nfcSession = nil
    }
}

// 扩展Data，方便十六进制字符串和Data互转
extension Data {
    init?(hexString: String) {
        let cleanedString = hexString.replacingOccurrences(of: " ", with: "")
        let length = cleanedString.count
        guard length % 2 == 0 else { return nil }
        var data = Data(capacity: length / 2)
        var index = cleanedString.startIndex
        while index < cleanedString.endIndex {
            let nextIndex = cleanedString.index(index, offsetBy: 2)
            let substring = cleanedString[index..<nextIndex]
            if let byte = UInt8(substring, radix: 16) {
                data.append(byte)
            } else {
                return nil
            }
            index = nextIndex
        }
        self = data
    }

    var hexString: String {
        return map { String(format: "%02X", $0) }.joined()
    }
}

关键说明 #

• 转换标签类型：只有将检测到的NFCTag转为NFCISO14443Tag，才能调用符合ISO 14443-4标准的sendCommand方法
• 指令转换：十六进制字符串需要先转为Data对象，上面的Data扩展提供了便捷的转换方法
• 错误处理：务必处理连接失败、标签类型不匹配、指令发送失败等场景，避免会话异常

内容的提问来源于stack exchange，提问作者pankot