Swift - Using a Timer to detect user inactivity then display an Alert after 4 minutes to prompt the user if they are still there - ios

Question

I have a basic application for iPads which consists of 4 views. Across the whole app, I want to be able to detect user inactivity and then display an Alert after 4 minutes which will ask the user if they are still there.
I have found some useful resources for the Timer and Alert functions. I have played around with these tutorials and can get the Timer working on it's own. However, this is my first time developing in Swift so I would like some guidance on the best way to connect the Timer to the Alert is? I would like the Timer to run for 4 minutes and then create the Alert.
I would also like to know where the best place is to put the code for these elements so that they work across all 4 of my views. E.g is there a single place I can put the code and reuse it rather than having it repeated in each of the 4 views?

Answer 1

First you can follow the instructions here to set up your timer: https://blog.gaelfoppolo.com/detecting-user-inactivity-in-ios-application-684b0eeeef5b
Then you can do something like this to handle the timeout notifications:
extension UIViewController {
func observeTimeout() {
NotificationCenter.default.addObserver(
self,
selector: #selector(handleTimeout),
name: .appTimeout,
object: nil)
}
#objc func handleTimeout() {
let alert = UIAlertController(title: "Timeout", message: "Oh no!", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { _ in
}))
present(alert, animated: true, completion: nil)
}
}
And then in each of your view controllers do this to register for the timeout:
class SomeViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
observeTimeout()
}
}

Answer 2

It's been a while since this question was asked however, since I came across the same problem I slightly changed the answer #rob-c provided using this guide:
Tested on Swift 5.5 and iOS 15.1
1- Create a subclass of UIApplication
import Foundation
import UIKit
class TimerApplication: UIApplication {
private var timeoutInSeconds: TimeInterval {
return 40.0
}
private var idleTimer: Timer?
override init() {
super.init()
resetIdleTimer()
}
private func resetIdleTimer() {
if let idleTimer = idleTimer {
idleTimer.invalidate()
}
idleTimer = Timer.scheduledTimer(timeInterval: timeoutInSeconds,
target: self,
selector: #selector(TimerApplication.timeHasExceeded),
userInfo: nil,
repeats: false
)
}
#objc private func timeHasExceeded() {
NotificationCenter.default.post(name: .appTimeout, object: nil)
}
override func sendEvent(_ event: UIEvent) {
super.sendEvent(event)
if idleTimer != nil {
self.resetIdleTimer()
}
if let touches = event.allTouches {
for touch in touches where touch.phase == UITouch.Phase.began {
self.resetIdleTimer()
}
}
}
}
2- Add notification name
import Foundation
extension Notification.Name {
static let appTimeout = Notification.Name("appTimeout")
}
3- Create main.swift file and add this
import Foundation
import UIKit
/// NOTE: comment out #UIApplicationMain in AppDelegate
UIApplicationMain(
CommandLine.argc,
CommandLine.unsafeArgv,
NSStringFromClass(TimerApplication.self),
NSStringFromClass(AppDelegate.self)
)
4- Remove #UIApplicationMain from AppDelegate
5- Add observer for the notification
Add the observer where appropriate for your case, in AppDelegate or any view controller:
func addObservers() {
NotificationCenter.default.addObserver(self,
selector: #selector(idleTimeLimitReached(_:)),
name: .appTimeout,
object: nil)
}
#objc func idleTimeLimitReached(_ notification: Notification) {
print("***** IDLE Time called")
}

Answer 3

You can run Timer in AppDelegate itself and display alert like below from AppDelegate
func showAlertFromAppDelegates(){
let alertVC = UIAlertController(title: "Oops" , message: "Presented Alert from AppDelegates", preferredStyle: UIAlertController.Style.alert)
let okAction = UIAlertAction(title: "Okay", style: UIAlertAction.Style.cancel) { (alert) in
}
alertVC.addAction(okAction)
var presentVC = self.window!.rootViewController
while let next = presentVC?.presentedViewController
{
presentVC = next
}
presentVC?.present(alertVC, animated: true, completion: nil)
}
Edit:
Timer related code added, call startTimer() when you want to start inactivity and call stopTimer() when inactivity ends
func startTimer()
{
let interval = 4*60
timer = Timer.scheduledTimer(timeInterval: TimeInterval(interval), target: self, selector: #selector(self.showAlertFromAppDelegates), userInfo: nil, repeats: true)
}
func stopTimer()
{
if let timer = timer
{
timer.invalidate()
}
timer = nil
}