ReadRSSI

import CoreBluetooth
import UIKit

class ViewController: UIViewController, CBCentralManagerDelegate, CBPeripheralDelegate {

    var centralManager: CBCentralManager!
    var peripheral: CBPeripheral!
    var currentCharacteristic: CBCharacteristic! = nil
    var readRSSITimer: NSTimer!
    var RSSIholder: NSNumber = 0
    
    func centralManager(central: CBCentralManager, didConnectPeripheral peripheral: CBPeripheral) {
        peripheral.readRSSI()
        self.startReadRSSI()
        peripheral.delegate = self
        peripheral.discoverServices(nil)
        print("connected to \(peripheral)")
        self.stopScan()
    }
    
    func peripheral(peripheral: CBPeripheral, didReadRSSI RSSI: NSNumber, error: NSError?) {
        self.RSSIholder = Int(RSSI)
    }
    
    func readRSSI(){
        if (self.peripheral != nil){
            self.peripheral.delegate = self
            self.peripheral.readRSSI()
        } else {
            print("peripheral = nil")
        }
        if (Int(self.RSSIholder) > -70) {
            let openValue = "1".dataUsingEncoding(NSUTF8StringEncoding)!
            self.peripheral.writeValue(openValue, forCharacteristic: self.currentCharacteristic, type: CBCharacteristicWriteType.WithResponse)
        }
    }
    
    func startReadRSSI() {
        if self.readRSSITimer == nil {
            self.readRSSITimer = NSTimer.scheduledTimerWithTimeInterval(0.5, target: self, selector: #selector(self.readRSSI), userInfo: nil, repeats: true)
        }
    }
    
    func stopReadRSSI() {
        if (self.readRSSITimer != nil){
            self.readRSSITimer.invalidate()
            self.readRSSITimer = nil
        }
    }
}