EventBus

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Overview

EventBus is a Swift library that simplifies the implementation of event-based programming. It allows you to define, subscribe to, and publish events with ease.

Key Features

• Define and publish events with type safety.
• Store subscriber objects with weak references to prevent memory leaks.
• Automatically remove the subscription when the subscriber object is deallocated.
• Provide a thread-safety implementation to prevent concurrency issues in a multi-threaded environment.

Installation

Swift Package Manager

To install EventBus via SPM, add the following to the dependencies value of your Package.swift.

dependencies:[.package(url:"https://github.com/swiftarium/EventBus.git", from:"1.1.1"),]

Then, specify "EventBus" as a dependency for the target that will use it.

targets:[.target(name:"YourTarget", dependencies:["EventBus"]),]

API Reference

EventProtocol

protocolEventProtocol{associatedtypePayloadvarpayload:Payload{get}}

EventProtocol is a protocol used to define new events. You can specify the type of Payload that will be sent when the event is triggered.

structUserLoggedInEvent:EventProtocol{typealiasPayload=Userletpayload:Payload}

You can define the Payload in various ways other than using typealias.

structUserLoggedInEvent:EventProtocol{structPayload{letuser:User}letpayload:Payload}

If you don't want to pass a Payload, use the Void type.

structUserLoggedInEvent:EventProtocol{letpayload:Void=()}

EventBus

/// Subscribe to a given event.
func on<Event>(Event.Type,(Event.Payload)-> Void)-> any SubscriptionToken
func on<Subscriber, Event>(Event.Type, by:Subscriber?, EventCallback<Subscriber, Event>)
/// Unsubscribe from a given event for a specific subscriber.
func off<Token, Event>(Event.Type, by:Token)func off<Subscriber, Event>(Event.Type, by: Subscriber)
/// Cancel all subscriptions for a given subscriber.
func reset<Subscriber>(by:Subscriber)
/// Publish a given event.
func emit<Event>(Event)

With EventBus, you can easily subscribe to and publish events. Access the shared instance through the shared type property.

// Subscribe
lettoken=EventBus.shared.on(UserLoggedInEvent.self){ user inprint("\(user.name) has logged in.")}
// Subscribe with a subscriber
EventBus.shared.on(UserLoggedInEvent.self, by:self){ subscriber, user inprint("\(user.name) has logged in.")}
// Publish
EventBus.shared.emit(UserLoggedInEvent(payload: user))

You can unsubscribe by providing either the SubscriptionToken or the subscriber object.

// Unsubscribe with a token
EventBus.shared.off(UserLoggedInEvent.self, by: token)
// Unsubscribe with a subscriber
EventBus.shared.off(UserLoggedInEvent.self, by:self)

You can cancel all event subscriptions by providing the subscriber object.

// Cancel all subscriptions
EventBus.shared.reset(by:self)

By passing EventBus.Config, you can create a new EventBus instance.

• tokenProvider: A closure that provides a token generator conforming to the SubscriptionToken protocol.
• cleanFrequency: Specifies the frequency to clean up the subscriptions. Passes the current subscriber count and returns a value of type DispatchTimeInterval.

letconfig=EventBus.Config(tokenProvider: customTokenProvider, cleanFrequency: customFrequency)letcustomEventBus=EventBus(config: config)

Testing

$ swift test

License

This library is released under the MIT license. See LICENSE for details.