Design Patterns: Mediator Pattern with Swift Programming Language
Design patterns are a great way to solve common problems in software development. One of the most popular design patterns is the Mediator Pattern. This pattern allows objects to communicate with each other without knowing about each other, and provides a centralized point of communication between multiple objects. In this article, we will look at how to implement the Mediator Pattern in Swift.
The Mediator Pattern can be used to reduce coupling between classes and is an important part of object-oriented design. It helps us to design loosely coupled systems which are easier to maintain and extend. The main idea behind the Mediator Pattern is that all communication between objects is handled through a central object, called the mediator. The mediator is responsible for handling all requests, and sending responses back to the appropriate objects.
In Swift, the Mediator Pattern can be implemented using protocols. A protocol defines the interface that all mediators must adhere to. This ensures that all mediators have the same methods and properties, and allows us to create a generic mediator class that can be used to handle any type of communication.
To start, let’s define a protocol for our mediator. Here, we’ll define a method called ‘sendMessage’ which takes two parameters – a sender object and a message object. This method will be responsible for sending the message from the sender to the appropriate objects.
protocol Mediator {
func sendMessage(sender: AnyObject, message: Any)
} Next, we need to create a class to act as our mediator. This class should conform to the Mediator protocol we just created. We’ll also add a property called ‘delegates’ which is an array of objects that the mediator will send messages to.
class MessageMediator: Mediator {
var delegates = [AnyObject]()
func sendMessage(sender: AnyObject, message: Any) {
// Send the message to all delegates
for delegate in delegates {
delegate.receiveMessage(sender: sender, message: message)
}
}
}Now that we have a mediator class, we need to create objects that can use it. We’ll create a simple Person class that can send messages to other Person objects.
class Person {
var name: String
var mediator: MessageMediator
init(name: String, mediator: MessageMediator) {
self.name = name
self.mediator = mediator
}
func send(message: String) {
mediator.sendMessage(sender: self, message: message)
}
func receive(sender: AnyObject, message: Any) {
print("\(name) received message: \(message)")
}
}Finally, we need to create an instance of our MessageMediator class, and add some Person objects to it.
let mediator = MessageMediator()
let john = Person(name: "John", mediator: mediator)
let jane = Person(name: "Jane", mediator: mediator)
let bob = Person(name: "Bob", mediator: mediator)
mediator.delegates.append(john)
mediator.delegates.append(jane)
mediator.delegates.append(bob)
john.send(message: "Hello World!")When john sends a message, the mediator will receive it and forward it to all of its delegates. In this case, jane and bob will both receive the message and print it out.
The Mediator Pattern is a great way to reduce coupling between objects and to provide a central point of communication. It allows us to easily add new objects to our system without having to modify existing code, and provides a clean and concise way to handle communication between objects.
Using protocols and classes, we can easily implement the Mediator Pattern in Swift. By defining a protocol for our mediator, we can ensure that all mediators have the same methods and properties, and can create a generic mediator class that can be used to handle any type of communication. With this pattern, we can create loosely coupled systems that are easier to maintain and extend.