Swift 3: Checking if app is in background - ios

Question

I need to check if the app is moved to the background. Why?
Well because my app works with bluetooth and only one person can be connected to this device at a time. Therefore if they are not using it and the app is in the background, disconnect them and send them to the connect main page.
Now I have accomplished this. I have a selector in the main first class and a function to disconnect and send to first page. But what I didn't realise is that if the control panel is dragged up, the app is in the 'background'.
From looking around there doesn't seem to be a way to detect if the control panel is brought up. So does anyone have any ideas on how I can do this differently?
Realistically I just want it so if the app is moved to the background for any other reason than the control panel being brought up, disconnect from the device.
Selector:
let notificationCenter = NotificationCenter.default
notificationCenter.addObserver(self, selector: #selector(appMovedToBackground), name: Notification.Name.UIApplicationWillResignActive, object: nil)
Function:
#objc func appMovedToBackground() {
if (ViewController.connectedPeripheral != nil) {
print("App moved to background!")
let storyBoard : UIStoryboard = UIStoryboard(name: "Main", bundle:nil)
let nextViewController = storyBoard.instantiateViewController(withIdentifier: "connectView") as! ViewController
self.navigationController?.pushViewController(nextViewController, animated: true)
ViewController.centralManager.cancelPeripheralConnection(ViewController.connectedPeripheral!)
}
else {
print("App moved to background but no device is connected so no further action taken")
}
}
This is not a duplicate of other questions. I know how to check if app is in background state. I just don't want to disconnect when the control panel is brought up...

Answer 1

In Swift:
if UIApplication.shared.applicationState == .background {
// Add code here...
}
In Objective-C:
if ([UIApplication sharedApplication].applicationState == UIApplicationStateBackground) {
// Add code here...
}
Hope it works!

Answer 2

Have you tried with adding observer to willResignActive in your view controller?
NotificationCenter.default.addObserver(self, selector: #selector(willResignActive), name: .UIApplicationWillResignActive, object: nil)
func willResignActive(_ notification: Notification) {
// code to execute
}

Answer 3

Then you can use this also. After entering in background state , app will be moved to inactive state.
override func viewDidLoad() {
super.viewDidLoad()
let app = UIApplication.shared
//Register for the applicationWillResignActive anywhere in your app.
NotificationCenter.default.addObserver(self, selector: #selector(ViewController.applicationWillResignActive(notification:)), name: NSNotification.Name.UIApplicationWillResignActive, object: app)
}
func applicationWillResignActive(notification: NSNotification) {
}