Best way to manage BLE central object - ios

Question

I am developing an app which is capable of doing something like this.
My app should connects with BLE peripheral and i want to keep monitoring the connection. when disconnects the connection it should take the locatoin and update the map. i need to track the disconnection even if the peripheral's switch off event in my App.
i have two View Controllers. One is for update my Google map. other one is a tableViewController which is listed available device list. i have implemented a BLE Manager using Singolton pattern.
class BleManager: NSObject , CBCentralManagerDelegate, CBPeripheralDelegate {
var centralManager: CBCentralManager?
var peripherals = Array<CBPeripheral>()
var periparal : CBPeripheral!
let dataSaver = DataSaver.sharedInstance
let locationMgr = LocationInfo.sharedInstance
var viewController : CarList!
static let shared = BleManager()
//MARK:- Initialiser
private override init() {
super.init()
centralManager = CBCentralManager(delegate: self, queue: DispatchQueue.main)
}
init(vc : CarList) {
super.init()
viewController = vc
//centralManager = CBCentralManager(delegate: self, queue: DispatchQueue.main)
}
//MARK:- BLE Activities
func startScanForDevices() {
peripherals = []
//self.centralManager?.scanForPeripherals(withServices: [CBUUID(string: "DFB0")], options: nil)
self.centralManager?.scanForPeripherals(withServices: nil, options: nil)
//self.centralManager?.scanForPeripherals(withServices: nil, options: [CBCentralManagerScanOptionAllowDuplicatesKey : true])
}
func stopScanForDevices() {
if centralManager != nil {
centralManager?.stopScan()
}
}
func connectToADevice(pheriperal : CBPeripheral){
periparal = pheriperal
// saving Connected Car in App LifeSycle
connectedCar = pheriperal
centralManager?.connect(pheriperal, options: nil)
(viewController != nil) ? viewController.devTable.reloadData() : print("")
}
func disconnectFromApp(pheriperal : CBPeripheral){
centralManager?.cancelPeripheralConnection(pheriperal)
}
//MARK:- BLE Central Delegates
func centralManagerDidUpdateState(_ central: CBCentralManager) {
if (central.state == .poweredOn){
startScanForDevices()
}
else if (central.state == .poweredOff){
print("Powered Off")
centralManager?.cancelPeripheralConnection(periparal)
}
else if (central.state == .resetting){
print("resetting")
}
else if (central.state == .unauthorized){
print("unauthorized")
}
else if (central.state == .unsupported){
print("unsupported")
}else{
print("Unknown")
}
}
func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
//peripherals.append(peripheral)
//print("DEVICES LIST : \(peripherals)")
updatePheriperals(device: peripheral)
if viewController != nil {
viewController.devTable.reloadData()
if dataSaver.isAnyCarHasBeenSaved() == true && dataSaver.getMyCarIdentification() == peripheral.identifier.uuidString && peripheral.state == .disconnected{
connectToADevice(pheriperal: peripheral)
viewController.devTable.reloadData()
}
}else{
if dataSaver.isAnyCarHasBeenSaved() == true && dataSaver.getMyCarIdentification() == peripheral.identifier.uuidString{
connectToADevice(pheriperal: peripheral)
}
}
}
func updatePheriperals(device : CBPeripheral) {
if peripherals.count != 0 {
for dev in peripherals {
if device.identifier != dev.identifier {
peripherals.append(device)
}
}
}else{
peripherals.append(device)
}
}
func centralManager(_ central: CBCentralManager, didDisconnectPeripheral peripheral: CBPeripheral, error: Error?) {
print("\(ConnectionState(rawValue: peripheral.state.rawValue)?.name()) \(peripheral.name) from App.. Taking Geo cordinates")
locationMgr.didFindLocation = false
locationMgr.getCurrentLocation()
if viewController != nil {
viewController.devTable.reloadData()
}else{
print("Just Updating Locations")
}
showNotification(message: peripheral.name! + " has been Disconnected from Find My Car" )
startScanForDevices()
}
func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {
print("\(ConnectionState(rawValue: peripheral.state.rawValue)?.name()) \(peripheral.name) to App.. Removeing previous location")
dataSaver.removeLocation()
dataSaver.saveMyCarIdentification(myCar: peripheral.identifier.uuidString)
(viewController != nil) ? viewController.devTable.reloadData() : print("Just Updating Locations")
//print("Service UUIDs : \(peripheral)")
NotificationCenter.default.post(name: NSNotification.Name(rawValue: AppStrings.updateMapString), object: nil)
showNotification(message: peripheral.name! + " has been connected to Find My Car" )
}
func centralManager(_ central: CBCentralManager, willRestoreState dict: [String : Any]) {
print("Already Connected Pheriperals : \(dict[CBCentralManagerRestoredStatePeripheralsKey])")
}
func centralManager(_ central: CBCentralManager, didFailToConnect peripheral: CBPeripheral, error: Error?) {
print("Failed To Connect with \(peripheral.name)")
centralManager?.cancelPeripheralConnection(peripheral)
}
In my MapViewController i use sharedInstance and start scanning
even in my TableViewController i do the same.
but sometimes when i try to switch off the peripheral device, my BLE Central does not called did disconnect peripheral delegate.
and i also wanna know how can i handle background scanning. with state prevention and restoration (I dont know anything about it. i just want to waork my app in background As same way in foreground)
Please help