从Swift上的kCBAdvDataManufacturerData中提取数据

Question

我有一个TI传感器Tag作为外设,以kCBAdvDataManufacturerData的形式广播BLE数据.我想从iOS中的这些数据中提取不同的值.

我在Swift中执行以下操作:

func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber){     
     for (index, foundPeripheral) in peripherals.enumerated(){
         if foundPeripheral.peripheral?.identifier == peripheral.identifier{
             peripherals[index].lastRSSI = RSSI
             print("AdvertisementData:\(advertisementData)")
             return

         }
     }  

     let isConnectable = advertisementData["kCBAdvDataIsConnectable"] as! Bool
     let displayPeripheral = DisplayPeripheral(peripheral: peripheral, lastRSSI: RSSI, isConnectable: isConnectable)
     peripherals.append(displayPeripheral)
     tableView.reloadData()
    }
}

这就是我在控制台中看到的:

AdvertisementData:["kCBAdvDataIsConnectable":0,"kCBAdvDataManufacturerData":<0d00fe05 0c6f32>,"kCBAdvDataLocalName":CLIMBC]

我有兴趣解码的数据是kCBAdvDataManufacturerData:<0d00fe05 0c6f32>并在屏幕上显示每个字段.具体来说,这就是数字代表我的情况:

1. 0d00 - TI制造商ID
2. fe - 我给出的节点ID
3. 05 - 节点的状态(保持不变的状态)
4. c6f - 是传感器标签电池电压
5. 32-是BLE包计数器.

在Android中,我可以解码如下:

private static String getNodeIdFromRawPacket(byte[] manufSpecField) {
    if(manufSpecField != null && manufSpecField.length > 1) {
        return String.format("%02X", manufSpecField[0]);
    }else{
        return null;
    }
}
private static int getNodeBatteryVoltageFromRawPacket(byte[] manufSpecField){
    if(manufSpecField != null && manufSpecField.length > 4) {
        return (((((int) manufSpecField[manufSpecField.length - 3]) << 24) >>> 24) << 8) + ((((int) manufSpecField[manufSpecField.length - 2]) << 24) >>> 24);
    }else{
        return 0;
    }
}

private byte[] extractManufacturerSpecificData(byte[] scanRecord, int manufacturer_id){

     if(scanRecord != null) {
         int ptr = 0;
         while (ptr < scanRecord.length && scanRecord[ptr] != 0) {
             int field_length = scanRecord[ptr];
             if (scanRecord[ptr + 1] == (byte) (0xFF)) { //this is true when the manufacturer specific data field has been found
                 if (((scanRecord[ptr + 3] << 8) + scanRecord[ptr + 2]) == manufacturer_id) {
                    byte[] manufacturerSpecificData = new byte[field_length - 3];
                     System.arraycopy(scanRecord, ptr + 4, manufacturerSpecificData, 0, field_length - 3);
                     return manufacturerSpecificData;
                 }
             }
             ptr += (field_length + 1);
         }
         return null;
     }else{
        return null;
     }
  }
};

我怎样才能做到这一点？我是Swift的新手,这就是我找到一些困难的原因.任何代码段都是最受欢迎的.

Answer 1

看到控制台的输出,advertisementData["kCBAdvDataManufacturerData"]似乎是一个NSData包含7个字节.您可以轻松地将其作为Swift访问Data,并且Data可以使用下标访问a中的每个字节:

if let manufacturerData = advertisementData["kCBAdvDataManufacturerData"] as? Data {
    assert(manufacturerData.count >= 7)
    //0d00 - TI manufacturer ID
    //Constructing 2-byte data as little endian (as TI's manufacturer ID is 000D)
    let manufactureID = UInt16(manufacturerData[0]) + UInt16(manufacturerData[1]) << 8
    print(String(format: "%04X", manufactureID)) //->000D
    //fe - the node ID that I have given
    let nodeID = manufacturerData[2]
    print(String(format: "%02X", nodeID)) //->FE
    //05 - state of the node (something that remains constant
    let state = manufacturerData[3]
    print(String(format: "%02X", state)) //->05
    //c6f - is the sensor tag battery voltage
    //Constructing 2-byte data as big endian (as shown in the Java code)
    let batteryVoltage = UInt16(manufacturerData[4]) << 8 + UInt16(manufacturerData[5])
    print(String(format: "%04X", batteryVoltage)) //->0C6F
    //32- is the BLE packet counter.
    let packetCounter = manufacturerData[6]
    print(String(format: "%02X", packetCounter)) //->32
}

Answer 2

下面是 swift 3 Data 方法的实现，subdata其中包含一个将字符串转换为数据然后拆分为可转换回字符串的字节的示例：

let input = "505450578"
let data = input.data(using: .utf8)

let manufacturerId:Range<Int> = 0..<2
let nodeId:Range<Int> = 2..<4
let nodeState:Range<Int> = 4..<5
let voltage:Range<Int> = 5..<6
let packetCounter:Range<Int> = 6..<9

let subdata1 = data?.subdata(in: manufacturerId)
let subdata2 = data?.subdata(in: nodeId)
let subdata3 = data?.subdata(in: nodeState)
let subdata4 = data?.subdata(in: voltage)
let subdata5 = data?.subdata(in: packetCounter)

//Results from original given string
let str1 = String(data: subdata1!, encoding:.utf8) //50
let str2 = String(data: subdata2!, encoding:.utf8) //54
let str3 = String(data: subdata3!, encoding:.utf8) //5
let str4 = String(data: subdata4!, encoding:.utf8) //0
let str5 = String(data: subdata5!, encoding:.utf8) //578