Events.swift

//
//  Events.swift
//  Updated for Swift 6.2 with Xcode 6.3 beta 2
//
//  Copyright (c) 2014 Stephen Haney
//  MIT License
//
import Foundation

class EventManager {
    // using NSMutableArray as Swift arrays can't change size inside dictionaries (yet, probably)
    var listeners = Dictionary<String, NSMutableArray>();
    
    // Create a new event listener, not expecting information from the trigger
    // + eventName: Matching trigger eventNames will cause this listener to fire
    // + action: The block of code you want executed when the event triggers
    func listenTo(eventName:String, action: @escaping (()->())) {
        let newListener = EventListenerAction(callback: action);
        addListener(eventName: eventName, newEventListener: newListener);
    }
    
    // Create a new event listener, expecting information from the trigger
    // + eventName: Matching trigger eventNames will cause this listener to fire
    // + action: The block of code you want executed when the event triggers
    func listenTo(eventName:String, action: @escaping ((Any?)->())) {
        let newListener = EventListenerAction(callback: action);
        addListener(eventName: eventName, newEventListener: newListener);
    }
    
    internal func addListener(eventName:String, newEventListener:EventListenerAction) {
        if let listenerArray = self.listeners[eventName] {
            // action array exists for this event, add new action to it
            listenerArray.add(newEventListener);
        }
        else {
            // no listeners created for this event yet, create a new array
            self.listeners[eventName] = [newEventListener] as NSMutableArray;
        }
    }
    
    // Removes all listeners by default, or specific listeners through paramters
    // + eventName: If an event name is passed, only listeners for that event will be removed
    func removeListeners(eventNameToRemoveOrNil:String?) {
        if let eventNameToRemove = eventNameToRemoveOrNil {
            // remove listeners for a specific event
            
            if let actionArray = self.listeners[eventNameToRemove] {
                // actions for this event exist
                actionArray.removeAllObjects();
            }
        }
        else {
            // no specific parameters - remove all listeners on this object
            self.listeners.removeAll(keepingCapacity: false);
        }
    }
    
    // Triggers an event
    // + eventName: Matching listener eventNames will fire when this is called
    // + information: pass values to your listeners
    func trigger(eventName:String, information:Any? = nil) {
        if let actionObjects = self.listeners[eventName] {
            for actionObject in actionObjects {
                if let actionToPerform = actionObject as? EventListenerAction {
                    if let methodToCall = actionToPerform.actionExpectsInfo {
                        methodToCall(information);
                    }
                    else if let methodToCall = actionToPerform.action {
                        methodToCall();
                    }
                }
            }
        }
    }
}

// Class to hold actions to live in NSMutableArray
class EventListenerAction {
    let action:(() -> ())?;
    let actionExpectsInfo:((Any?) -> ())?;
    
    init(callback: @escaping (() -> ()) ) {
        self.action = callback;
        self.actionExpectsInfo = nil;
    }
    
    init(callback: @escaping ((Any?) -> ()) ) {
        self.actionExpectsInfo = callback;
        self.action = nil;
    }
}