iOS CoreBluetooth写入Zebra ZD421D BLE打印机特征无响应问题

我查了各种教程和帮助文档，还是解决不了这个问题。我买了一台带BLE蓝牙的Zebra ZD421D标签打印机，现在开发自定义iOS应用实现打印功能。目前已经能发现设备、成功连接，也能获取服务和特征，但调用WriteValue写入特征值时，打印机完全没反应。我试了所有找到的特征，结果都一样。

为了排查是不是代码的问题，我用LightBlue应用测试，同样能找到并连接打印机，选特征写入新值后，打印机还是没反应，这让我很困惑。

我不确定是不是打印机配置的问题，查了Zebra打印机设置应用，但没找到相关解决选项。

我的Swift代码 #

import SwiftUI
import CoreBluetooth

class BluetoothViewModel: NSObject, ObservableObject {
    private var centralManager: CBCentralManager?
    private var peripherals: [CBPeripheral] = []
    private var printerPeripheral: CBPeripheral!
    @Published var peripheralNames: [String] = []

    override init() {
        super.init()
        self.centralManager = CBCentralManager(delegate: self, queue: .main)
    }
}

extension BluetoothViewModel: CBCentralManagerDelegate, CBPeripheralDelegate {
    func centralManagerDidUpdateState(_ central: CBCentralManager) {
        if central.state == .poweredOn {
            self.centralManager?.scanForPeripherals(withServices: nil)
        }
    }
    
    func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
        if !peripherals.contains(peripheral) {
            self.peripherals.append(peripheral)
            self.peripheralNames.append(peripheral.name ?? "Unnamed Device")
            
            if (peripheral.identifier.uuidString == "F9FC7DFB-F149-4F95-7CEF-D6596338D032") {
                centralManager?.connect(peripheral, options: nil)
                self.printerPeripheral = peripheral
                self.printerPeripheral.delegate = self
                
                print("connecting to \(peripheral.name ?? \"Unnamed Device\")")
                centralManager?.stopScan()
            }
        }
    }
    
    func centralManager(_ central: CBCentralManager, didFailToConnect peripheral: CBPeripheral, error: Error?) {
        print("Failed to connect to \(peripheral). (\(error!.localizedDescription))")
    }
    
    func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {
        if peripheral == self.printerPeripheral {
            print("Connected to your printer")
            peripheral.discoverServices(nil)
        }
    }
    
    func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
        print("didDiscoverServices")
        if let services = peripheral.services {
            for service in services {
                print("Service - \(service.uuid.uuidString) - \(service.description)")
                if service.uuid.uuidString.elementsEqual("38EB4A80-C570-11E3-9507-0002A5D5C51B") {
                    print("Printer service found")
                    peripheral.discoverCharacteristics(nil, for: service)
                }
            }
        }
    }
    
    func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
        print("didDiscoverCharactericsFor")
        if let characteristics = service.characteristics {
            print(characteristics.count)
            for characteristic in characteristics {
                print("Characteristic - \(characteristic.uuid)")
                if (characteristic.uuid.uuidString.elementsEqual("38EB4A82-C570-11E3-9507-0002A5D5C51B")) {
                    print("write")
                    var data: String = "test"
                    let valueString = (data as NSString).data(using: String.Encoding.utf8.rawValue)
                    peripheral.writeValue(valueString!, for: characteristic, type: .withResponse)
                    
                    print("Value String===>\(valueString.debugDescription)")
                }
            }
        }
    }
    
    func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?) {
        guard error == nil else {
            print("Fejl \(error)")
          return
        }
         print("Message sent")
    }
}


struct ContentView: View {
    @ObservedObject private var bluetoothViewModel = BluetoothViewModel()
    
    var body: some View {
        NavigationView {
            List(bluetoothViewModel.peripheralNames, id: \.self) {
                Text($0)
                    .navigationTitle("Peripherals")
            }
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

控制台输出 #

connecting to D8J222507660
Connected to your printer
didDiscoverServices
Service - 180A - <CBService: 0x280250580, isPrimary = YES, UUID = Device Information>
Service - 38EB4A80-C570-11E3-9507-0002A5D5C51B - <CBService: 0x2802502c0, isPrimary = YES, UUID = 38EB4A80-C570-11E3-9507-0002A5D5C51B>
Printer service found
didDiscoverCharactericsFor
6
Characteristic - 38EB4A81-C570-11E3-9507-0002A5D5C51B
Characteristic - 38EB4A82-C570-11E3-9507-0002A5D5C51B
write
Value String===&gt;6 bytes
Characteristic - 38EB4A83-C570-11E3-9507-0002A5D5C51B
Characteristic - 38EB4A84-C570-11E3-9507-0002A5D5C51B
Characteristic - 38EB4A87-C570-11E3-9507-0002A5D5C51B
Characteristic - 38EB4A88-C570-11E3-9507-0002A5D5C51B
Message sent

我尝试通过自定义应用和LightBlue写入值，打印机均无反应。

内容的提问来源于stack exchange，提问作者frigsfrogs