Heart Rate Monitor Example(Swift)

gistfile1.swift

import UIKit
import CoreBluetooth

class ViewController: UIViewController, CBCentralManagerDelegate, CBPeripheralDelegate {
    
    let centralManager:CBCentralManager!
    var connectingPeripheral:CBPeripheral!
    
    required init(coder aDecoder: NSCoder) {
        
        super.init(coder: aDecoder)
        centralManager = CBCentralManager(delegate: self, queue: dispatch_get_main_queue())
    }
    
    func centralManagerDidUpdateState(central: CBCentralManager!){
        
        switch central.state{
        case .PoweredOn:
            println("poweredOn")
            
            let serviceUUIDs:[AnyObject] = [CBUUID(string: "180D")]
            let lastPeripherals = centralManager.retrieveConnectedPeripheralsWithServices(serviceUUIDs)
            
            if lastPeripherals.count > 0{
                let device = lastPeripherals.last as CBPeripheral;
                connectingPeripheral = device;
                centralManager.connectPeripheral(connectingPeripheral, options: nil)
            }
            else {
                centralManager.scanForPeripheralsWithServices(serviceUUIDs, options: nil)
            }
            
        default:
            println(central.state)
        }
    }
    
    func centralManager(central: CBCentralManager!, didDiscoverPeripheral peripheral: CBPeripheral!, advertisementData: [NSObject : AnyObject]!, RSSI: NSNumber!) {
        
        connectingPeripheral = peripheral
        connectingPeripheral.delegate = self
        centralManager.connectPeripheral(connectingPeripheral, options: nil)
    }
    
    func centralManager(central: CBCentralManager!, didConnectPeripheral peripheral: CBPeripheral!) {
        
        peripheral.discoverServices(nil)
    }
    
    func peripheral(peripheral: CBPeripheral!, didDiscoverServices error: NSError!) {
        
        if let actualError = error{
            
        }
        else {
            for service in peripheral.services as [CBService]!{
                peripheral.discoverCharacteristics(nil, forService: service)
            }
        }
    }
    
    func peripheral(peripheral: CBPeripheral!, didDiscoverCharacteristicsForService service: CBService!, error: NSError!) {
        
        if let actualError = error{
            
        }
        else {
            
            if service.UUID == CBUUID(string: "180D"){
                for characteristic in service.characteristics as [CBCharacteristic]{
                    switch characteristic.UUID.UUIDString{
                        
                    case "2A37":
                        // Set notification on heart rate measurement
                        println("Found a Heart Rate Measurement Characteristic")
                        peripheral.setNotifyValue(true, forCharacteristic: characteristic)
                        
                    case "2A38":
                        // Read body sensor location
                        println("Found a Body Sensor Location Characteristic")
                        peripheral.readValueForCharacteristic(characteristic)
                        
                    case "2A39":
                        // Write heart rate control point
                        println("Found a Heart Rate Control Point Characteristic")
                        
                        var rawArray:[UInt8] = [0x01];
                        let data = NSData(bytes: &rawArray, length: rawArray.count)
                        peripheral.writeValue(data, forCharacteristic: characteristic, type: CBCharacteristicWriteType.WithoutResponse)
                        
                    default:
                        println()
                    }
                    
                }
            }
        }
    }
    
    func update(#heartRateData:NSData){
        
        var buffer = [UInt8](count: heartRateData.length, repeatedValue: 0x00)
        heartRateData.getBytes(&buffer, length: buffer.count)
        
        var bpm:UInt16?
        if (buffer.count >= 2){
            if (buffer[0] & 0x01 == 0){
                bpm = UInt16(buffer[1]);
            }else {
                bpm = UInt16(buffer[1]) << 8
                bpm =  bpm! | UInt16(buffer[2])
            }
        }
        
        if let actualBpm = bpm{
            println(actualBpm)
        }else {
            println(bpm)
        }
    }
    
    func peripheral(peripheral: CBPeripheral!, didUpdateValueForCharacteristic characteristic: CBCharacteristic!, error: NSError!) {
        
        if let actualError = error{
            
        }else {
            switch characteristic.UUID.UUIDString{
            case "2A37":
                update(heartRateData:characteristic.value)
                
            default:
                println()
            }
        }
    }
}

Maybe even to Swift 3!

@nolili @moonvader @gertcuykens I just updated the syntax. It compiles on on Xcode 8.2 as of this comment:
https://github.com/jayliew/bluetoothPolarH7Swift/blob/master/bluetoothPolarH7/ViewController.swift