Basic throttle function in Swift

throttle.swift

//
// trottle.swift
//

import Foundation

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