Swift 3: Checking if app is in background

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...

Is the UIApplicationDidEnterBackground notification what you are looking for? — Martin R, Jul 25 '17 at 07:50

score 5 · Answer 1 · answered Jul 25 '17 at 21:35

5

In Swift:

if UIApplication.shared.applicationState == .background {
    // Add code here...
}

In Objective-C:

if ([UIApplication sharedApplication].applicationState == UIApplicationStateBackground) {
    // Add code here...
}

Hope it works!

answered Jul 25 '17 at 21:35

ppalancica

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score 1 · Answer 2 · answered Jul 25 '17 at 07:51

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
}

score 0 · Answer 3 · answered Jul 25 '17 at 07:52

0

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) {

}

answered Jul 25 '17 at 07:52

Appreciate the comment. I already have this. The real question is, how can we detect the control panel is brought up...but I guess there isn't a way. – jackabe Jul 25 '17 at 10:27
No there is no other way to detect reason why app is moving to background. – Jul 25 '17 at 13:13

Swift 3: Checking if app is in background

3 Answers3