Design Patterns in Swift — Mediator

The Mediator design pattern is a behavioral design pattern that allows objects to communicate with each other without having direct references to each other. The pattern introduces a mediator object that acts as a facilitator for communication between objects.

Here’s an example of using the Mediator pattern in Swift to control communication between different Airplane objects:

protocol Airplane {
    var name: String { get }
    func receive(message: String, from: Airplane)
    func send(message: String, to: Airplane)
}

class Boeing747: Airplane {
    var name: String = "Boeing 747"
    private var mediator: AirTrafficControl

    init(mediator: AirTrafficControl) {
        self.mediator = mediator
        self.mediator.register(plane: self)
    }
    
    func receive(message: String, from: Airplane) {
        print("\(name) received message: '\(message)' from \(from.name)")
    }
    
    func send(message: String, to: Airplane) {
        mediator.send(message: message, from: self, to: to)
    }
}

class AirTrafficControl {
    private var airplanes: [Airplane] = []
    
    func register(plane: Airplane) {
        airplanes.append(plane)
    }
    
    func send(message: String, from: Airplane, to: Airplane) {
        to.receive(message: message, from: from)
    }
}

let atc = AirTrafficControl()
let boeing747_1 = Boeing747(mediator: atc)
let boeing747_2…