Continually running UIButton every minute even app is minimized - ios

Question

I tried to run UIButton every minute when app is minimized. Therefore, I wrote a scheduledTimer function to run the button every 1 minute in Appdelegate, but it doesn't work, the error shows developeLocationHistoryButton:]: unrecognized selector sent to instance 0x60000024ee80. Please give me some guidance. My code is shown below.
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, CLLocationManagerDelegate {
var window: UIWindow?
var backgroundUpdateTask: UIBackgroundTaskIdentifier!
var backgroundTaskTimer: Timer! = Timer()
func doBackgroundTask() {
DispatchQueue.global(qos: .default).async {
self.beginBackgroundTask()
if self.backgroundTaskTimer != nil {
self.backgroundTaskTimer.invalidate()
self.backgroundTaskTimer = nil
}
//Making the app to run in background forever by calling the API
self.backgroundTaskTimer = Timer.scheduledTimer(timeInterval: 60, target:self , selector: #selector(ViewController.HistoryButton(_:)), userInfo: nil, repeats: true)
RunLoop.current.add(self.backgroundTaskTimer, forMode: RunLoopMode.defaultRunLoopMode)
RunLoop.current.run()
self.endBackgroundTask()
}
}
func beginBackgroundTask() {
self.backgroundUpdateTask = UIApplication.shared.beginBackgroundTask(withName: "test7", expirationHandler: {
self.endBackgroundTask()
})
}
func endBackgroundTask() {
UIApplication.shared.endBackgroundTask(self.backgroundUpdateTask)
self.backgroundUpdateTask = UIBackgroundTaskInvalid
}
I added self.doBackgroundTask() in ApplicationDidEnterBackground, and in ApplicationWillEnterForeground, I added
if self.backgroundTaskTimer != nil {
self.backgroundTaskTimer.invalidate()
self.backgroundTaskTimer = nil

Answer 1

The error you are getting means that you are trying to call a method on an object that doesn’t implement it. Your problem lies in this line
Timer.scheduledTimer(timeInterval: 60, target:self , selector: #selector(ViewController.HistoryButton(_:)), userInfo: nil, repeats: true)
And precisely with target: self, selector: #selector(ViewController.HistoryButton(_:)) part. self here is the instance of AppDelegate and you are teling the timer to call a method named HistoryButton(_:) on it. But that method is defined on a objects of type ViewController - which is clearly stated in the selector.
To resolve your issue you can either
Instantiate the ViewController and pass it as target - not recommend, as this is prone to side effects.
Copy the method to the AppDelegate and update your selector argument - better, but you have repeated code and will need to update it in both places if needed.
Extract the method to an outside class and use it in both places (the AppDelegate and ViewController)

Answer 2

You can't do what you are trying to do. If you request background time using UIApplication's beginBackgroundTask(withName:expirationHandler:) method you get 3 minutes, and after that your app will get suspended anyway. The best you'll be able to do is to have your app's timer run for 3 minutes.
There is a lot wrong with your code.
You try to add a Timer with a target of self and a selector of ViewController.HistoryButton(_:), but:
The current class is class AppDelegate, which does not have a method called HistoryButton(_:). (Also note that method names should start with lower-case letters.)
Another thing. This code:
var backgroundTaskTimer: Timer! = Timer()
Makes no sense. There's no reason to create a Timer in that code. Make it an optional and don't assign a timer to it:
var backgroundTaskTimer: Timer?
If you create a timer using scheduledTimer(), there's no need to then add it to the current run loop, so get rid of the lines that begins Runloop.current... and the line RunLoop.current.run()
Another thing: Why do you call self.endBackgroundTask() immediately after beginning your background task?
There are other things wrong with your code, but that's a start. It's fundamentally flawed. You're trying to tackle things you clearly don't fully grasp yet. I suggest slowing down and learning the things you're trying to do bit by bit.