Simple Debouncer in Swift 4

Debouncer.swift

//
//  Debouncer.swift
//
//  Created by Sam Oakley on 20/03/2019.
//

import Foundation

class Debouncer {
    
    private static var pendingRequestWorkItems: [AnyHashable: DispatchWorkItem] = [:]
    
    static func perform(context: AnyHashable, after: DispatchTimeInterval, block: @escaping () -> Void) {
        let pendingRequestWorkItem = pendingRequestWorkItems[context]
        pendingRequestWorkItem?.cancel()
        
        let requestWorkItem = DispatchWorkItem(block: block)
        pendingRequestWorkItems[context] = requestWorkItem
        DispatchQueue.main.asyncAfter(deadline: .now() + after,
                                      execute: requestWorkItem)
    }
}

"Debouncing" is the process by, if there are multiple, rapid calls to a function, only the final one will actually be executed. The perfect example is a web search that happens as the user types - you want to avoid making a call for every character that is entered, but still fire the request without having to hit a "search" button. This way, once the after duration expires with no more calls, the block is run. The context defines the type of the action.

https://open.spotify.com/track/3FzKPS0oVknVlCW3PhxIHl?si=TAs7ZdPvTcGwDnQRGpKq0g