Best solution to enhance timer in SwiftUI

SwiftUITimer.swift

//
//  SwiftUITimer.swift
//  
//
//  Created by Hai Kieu on 7/13/23.
//  https://medium.com/@programmingpassion/best-solution-to-enhance-timer-in-swiftui-501096572139

import SwiftUI
import Combine

extension View {
    public func onTimerFired(_ handler: Binding<Cancellable?>, every: TimeInterval, repeat: Bool, onCallback callback: @escaping ((Cancellable)->Void)) -> some View {
        self.modifier(TimerModifier(handler, every: every, repeat: `repeat`, onCallback: callback))
    }
}

struct TimerModifier: ViewModifier {
    
    // Declare an idle timer
    @State private var timer: Timer.TimerPublisher
    // A handler to help cancel a timer later
    @Binding private var handler: Cancellable?
    
    private let `repeat`: Bool
    private let every: TimeInterval
    private let callback: ((Cancellable)->Void)
  
    init(_ handler: Binding<Cancellable?>, every: TimeInterval, repeat: Bool, onCallback callback: @escaping ((Cancellable)->Void) ) {
      
          self.callback = callback
          self.every = every
          self.`repeat` = `repeat`
          
          let publisher = Timer.publish(every: every, on: .main, in: .default)
          _timer = .init(initialValue: publisher)
          _handler = handler
    }
    
    public func body(content: Content) -> some View {
        ZStack {
            content
        }.onAppear(perform: {
            setTimer()
        }).onReceive(timer) { timer in
            if !`repeat` { cancelTimer() }
            callback(handler)
        }
    }
    
    private func setTimer() {
      handler?.cancel()
      timer = Timer.publish(every: every, on: .main, in: .default)
      handler = timer.connect()
    }

    private func cancelTimer() {
      handler?.cancel()
    }
}


struct ConsumerDemoView: View {
    
    @State private var timerHandler: Cancellable?
    
    @State private var displayText: String = "Hello, world!"
    
    @State private var count: Int = 0
    
    var body: some View {
        VStack {
            Text(displayText)
                .padding()
        }.onTimerFired($timerHandler, every: 10, repeat: true) { timerHandler in
            count += 1
            displayText = "Timer fired \(count) times"
        }
    }
}

Changed: callback(handler)
to
if let handler {
callback( handler )
}

To prevent error: Value of optional type '(any Cancellable)?' must be unwrapped to a value of type 'any Cancellable'

can you add a interval modifier? Tried but the code but it don't really understand it.