Configure Beacons with CoreBluetooth

Introduction

Hot to read and write data to a bluetooth low energy device.

Remarks

Some important points

No capabilities are needed.
iPhone store bytes in Little Endian format, so check if bluetooth accessory use Little Endian too. Example:

- intel CPU usually use little endian.
- The ARM architecture was little-endian before version 3 when it became big-endian.

After a single or batch operation the connection will be lost, so you have to reconnect before continue.

Scan for SERVICE UUID

func SearchBLE(){
    cb_manager.scanForPeripherals(withServices:[service_uuid], options: nil)
    StopSearchBLE()
}

How to discover SERVICE UUID without documentation

func centralManager(_ central: CBCentralManager, didConnect peripheral:             
CBPeripheral) {
        peripheral.delegate = self
        peripheral.discoverServices(nil)
}

func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
    for service in peripheral.services! {
        print("Service: \(service)\n error: \(error)")
    }
}

discoverServices(nil) - NIL means that all services will be returned, which is not a good option.( READ Remarks 3)
If you haven’t found the SERVICE UUID run your code and looking for in console
I found have 3 services: Battery, Device information (Firmware) and FFF0
This uuid service isn’t a standard one, a list with standards can find here
FFF0 is the SERVICE UUID in this case

Convert data to UInt16 and contrary

Add this extensions to your class

protocol DataConvertible {
    init?(data: Data)
    var data: Data { get }
}

extension DataConvertible {

    init?(data: Data) {
        guard data.count == MemoryLayout<Self>.size else { return nil }
        self = data.withUnsafeBytes { $0.pointee }
    }

    var data: Data {
        var value = self
        return Data(buffer: UnsafeBufferPointer(start: &value, count: 1))
    }
}
extension UInt16 : DataConvertible {
    init?(data: Data) {
        guard data.count == MemoryLayout<UInt16>.size else { return nil }
        self = data.withUnsafeBytes { $0.pointee }
    }
    var data: Data {
        var value = CFSwapInt16HostToBig(self)
        return Data(buffer: UnsafeBufferPointer(start: &value, count: 1))
    }
}

Found a mistake? Have a question or improvement idea? Let me know.

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