Basic debounce function in Swift

debounce.swift

//
// debounce.swift
//

import Fundation

func debounce(delay: TimeInterval, queue: DispatchQueue = .main, action: @escaping (() -> Void)) -> () -> Void {
    var currentWorkItem: DispatchWorkItem?
    var lastFire: TimeInterval = 0
    
    return {
        let now = Date().timeIntervalSinceReferenceDate
        let remainingDelay = lastFire + delay - now
        let workItem = DispatchWorkItem(block: action)
        
        if remainingDelay > 0 {
            currentWorkItem?.cancel()
            queue.asyncAfter(deadline: .now() + remainingDelay, execute: workItem)
        } else {
            queue.asyncAfter(deadline: .now() + delay, execute: workItem)
            lastFire = now
        }
        
        currentWorkItem = workItem
    }
}