如何更改使用核心蓝牙ios扫描外围设备时发现的特征ID的顺序

Question

I am using core bluetooth framework in ios and scanning and discovering 2 charateristics ID but i want their order to be different then what I am getting so is it possible to change their order or anything programmatically?

code

   if (service.UUID.isEqual(CBUUID.UUIDWithString("F4F2-BC76-3206341A")))
    {
        println(service.characteristics.count)
        for aChar:CBCharacteristic in service.characteristics as [CBCharacteristic]

        {
            println(aChar)
            println(aChar.UUID)

            /* Write data*/
            if aChar.UUID.isEqual(CBUUID.UUIDWithString("D0F0AECD-6405-0B040047"))
            {
                var str:NSString = "heyaa..!!"
                data = str.dataUsingEncoding(NSUTF8StringEncoding)!
                peripheral.writeValue(data, forCharacteristic: aChar, type: CBCharacteristicWriteType.WithResponse)
                println("Write performed")
            }

            /* read data  */
            if aChar.UUID.isEqual(CBUUID.UUIDWithString("C8853E-A248-C6F0B1"))
            {
                peripheral.readValueForCharacteristic(aChar)
                println("Read performed")
            }
        }
    }

In this characteristics ID for reading data is getting called first but i want to call write data characteristics ID first so is there any way to resolve. Please help me out. Thank you in advance.

Answer 1

The characteristics will be discovered in an arbitrary and undefined order, but that shouldn't matter.

You should store a reference to the discovered characteristics so that you can write to them as required.

You app should go through distinct phases

1. Scan for and discover peripherals advertising specific service(s)
2. Connect to the target peripheral
3. Discover the characteristics of the service
4. Read/Write data as required - repeat this step as required
5. Disconnect

For example:

    var writeCharacteristic : CBCharacteristic?
    var readCharacteristic : CBCharacteristic?

    optional func peripheral(_ peripheral: CBPeripheral!, didDiscoverCharacteristicsForService service: CBService!,error error: NSError!) {    

      if (service.UUID.isEqual(CBUUID.UUIDWithString("F4F2-BC76-3206341A"))) 
      {

        println(service.characteristics.count)
        for aChar:CBCharacteristic in service.characteristics as [CBCharacteristic]

        {
            println(aChar)
            println(aChar.UUID)

            /* Write data*/
            if aChar.UUID.isEqual(CBUUID.UUIDWithString("D0F0AECD-6405-0B040047"))
            {
                self.writeCharacteristic=aChar
            }
            else if aChar.UUID.isEqual(CBUUID.UUIDWithString("C8853E-A248-C6F0B1"))
            {
                self.readCharacteristic=aChar

            }
        }
      }
      if (self.writeCharacteristic != nil && self.readCharacteristic != nil) {
            var str:NSString = "heyaa..!!"
            data = str.dataUsingEncoding(NSUTF8StringEncoding)!
            peripheral.writeValue(data, forCharacteristic: self.writeCharacteristic!, type: CBCharacteristicWriteType.WithResponse)
            println("Write performed")
      }
    }

    optional func peripheral(_ peripheral: CBPeripheral!,didWriteValueForCharacteristic characteristic: CBCharacteristic!,error error: NSError!) {
       peripheral.readValueForCharacteristic(self.readCharacteristic!)
       println("Read performed")
    }