Swift Timer How to invoke timer calls when app goes off-line

I have timer based code running perfectly when the app is running. Both the timer based functions get called and I am able to access and update iCloud. But if accidentally app goes off-line or user kills it, the timer code cannot be invoked. Is there a off-line mechanism, or some technique anyone can suggest that will allow to recollect and invoke pre-defined timer calls and execute the associated code?

let currentDateTime = Date()
        
let calendar = Calendar.current
        var tempDateTime1 = calendar.date(byAdding: .minute, value: 1, to: currentDateTime)
        var tempDateTime2 = calendar.date(byAdding: .minute, value: 2, to: currentDateTime)

    DispatchQueue.main.async {
   
        let userInfo:Dictionary<String, String> = ["tag": orderCkRecordName]
        
        let startTimer = Timer(fireAt: tempDateTime1!, interval: 0.0, target: self, selector: #selector(self.beginOrderUpdate(sender:)), userInfo: userInfo as Dictionary, repeats: false)
        
        let endTimer = Timer(fireAt: tempDateTime2!, interval: 0.0, target: self, selector: #selector(self.endOrderUpdate(sender:)), userInfo: userInfo as Dictionary, repeats: false)
        
        RunLoop.current.add(startTimer, forMode: RunLoopMode.commonModes)
        RunLoop.current.add(endTimer, forMode: RunLoopMode.commonModes)
    }