Simple abstraction for hud controller

HudController.swift

/// Controller for `HUD` visibility management.
/// Shows hud with delay to prevent interface blinking.
public class HudController {
    
    // MARK: - Instance variables
    
    private let container: UIView
    private let delay: DispatchTimeInterval
  
    private var hud: UIActivityIndicatorView?
    private var showHudWork: DispatchWorkItem?
    
    // MARK: - Public
    
    public init(
        container: UIView,
        delay: DispatchTimeInterval = .milliseconds(300)
    ) {
        self.container = container
        self.delay = delay
    }
    
    public func setHud(visible: Bool) {
        visible ? showIfNeeded() : hideIfNeeded()
    }
    
    // MARK: - Private
    
    private func showIfNeeded() {
        if hud != nil || showHudWork != nil {
            return
        }
        let showHudWork = DispatchWorkItem { [weak self] in
            self?.addHudToContainer()
        }
        self.showHudWork = showHudWork
        DispatchQueue.main.asyncAfter(
            deadline: .now() + delay,
            execute: showHudWork
        )
    }
    
    private func hideIfNeeded() {
        showHudWork?.cancel()
        showHudWork = nil
        
        hud?.stopAnimating()
        hud?.removeFromSuperview()
        hud = nil
    }
    
    private func addHudToContainer() {
        let hud = UIActivityIndicatorView(style: .large)
        self.hud = hud
        container.addSubview(hud)
        hud.startAnimating()
        showHudWork = nil
    }
}