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https://github.com/malcommac/RealEventsBus

🚎 Simple type-safe event bus implementation in swift
https://github.com/malcommac/RealEventsBus

eventbus notifications nsnotifications swift

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🚎 Simple type-safe event bus implementation in swift

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# 🚎 RealEventsBus



RealEventsBus is a small swift experiment package to implement a basic **type-safe event bus** mechanism.  

Some other implementations in GitHub are the sources of inspiration for this package.  



You can use it as replacement for standard `NSNotification`'s one-to-many messaging.

It uses GCD for messagings, it's thread-safe and, best of all, it's type safe.



## ⭐️ Feature Highlights



- It's **type safe**

- Implement **custom messages**; just set conformance to `Event` or `BufferedEvent` type

- Messages/observers are posted and registered in thread safe

- **Easy to use**; just one line to register and post events

- Supports for **buffered events** (get the last value published by a bus)



## 🕵️ How It Works



This example uses `enum` as datatype for event.  

Btw you can use any type you want as event, `struct` or `class` (see the other example below).

First of all we need to define a custom event; if your event is a group of different messages this is the best thing you can do:



```swift

public enum UserEvents: Event {

    case userDidLogged(username: String)

    case userLoggedOut

    case profileUpdated(fullName: String, age: Int)

}

```



Suppose you want to be notified about this kind of events in your `UIViewController`:



```swift

class ViewController: UIViewController {

    override func viewDidLoad() {

        super.viewDidLoad()



        Bus.register(self) { event in

            switch event {

            case .profileUpdated(let fullName, let age):

                print("Profile updated with '\(fullName)', which is \(age) old")

            case .userDidLogged(let username):

                print("User '\(username)' logged in")

            case .userLoggedOut:

                print("User logged out")

            }

        }

    }



    deinit {

        // While it's not required (it does not generate any leak) 

        // you may want to unregister an observer when it's not needed anymore.

        Bus.unregister(self)

    }

}

```



When you need to post new events to any registered obserer like the one above just use `post` function:



```swift

Bus.post(.userDidLogged(username: "danielemm"))

```



### BufferedEvent



If your event is conform to `BufferedEvent` instead of `Event` you can use the `lastValue()` function to get the latest posted value into the bus. It's like Rx.  

Moreover: when a new observer is registered it will receive the last value posted into the bus, if any.



This is an example.



First of all we define the message:



```swift

public class CustomEvent: BufferedEvent {

    

    var messageValue: String

    var options: [String: Any?]?

    

    public init(value: String, options: [String: Any?]) {

        self.messageValue = value

        self.options = options

    }



}

```



```swift

    // Post a new event

    Bus.post(.init(value: "Some message", options: ["a": 1, "b": "some"]))



    // At certain point in your code:

    let lastValue = Bus.lastValue() // print the type above!

```



### Custom Dispatch Queue



You can also specify a queue where the message callback will be called.  

By default the `.main` queue is used.



```swift

Bus.register(self, queue: .global()) { _ in // in background queue

   // do something

}        

```



## Install



### Swift Package Manager



To install it using the Swift Package Manager specify it as dependency in the Package.swift file:



```swift

dependencies: [

    .package(url: "https://github.com/malcommac/RealEventsBus.git", branch: "main"),

],

```



### CocoaPods



Not yet supported.



## Author 



This little experiment was created by [Daniele Margutti](mailto:[email protected]).  

If you like it you can fork or open a PR or report an issue.  

If you want to support my work just [take a look at my Github Profile](https://github.com/malcommac).



## License



It's the MIT license.