Swift adapter design sample – The.Swift.Dev.

Fist of all let me emphasize that, that is the true world illustration of what we’re going to construct on this little Swift adapter sample tutorial:

Adapter is a structural design sample that permits objects with incompatible interfaces to work collectively. In different phrases, it transforms the interface of an object to adapt it to a distinct object.

So adapter can remodel one factor into one other, typically it’s referred to as wrapper, as a result of it wraps the thing and offers a brand new interface round it. It’s like a software program dongle for particular interfaces or legacy courses. (Dongle haters: it’s time to go away the previous behind!) 😂

Adapter design sample implementation

Creating an adapter in Swift is definitely an excellent simple process to do. You simply have to make a brand new object, “field” the outdated one into it and implement the required interface in your new class or struct. In different phrases, a wrapper object might be our adapter to implement the goal interface by wrapping an different adaptee object. So once more:

Adaptee

The item we’re adapting to a selected goal (e.g. old-school USB-A port).

Adapter

An object that wraps the unique one and produces the brand new necessities specified by some goal interface (this does the precise work, aka. the little dongle above).

Goal

It’s the object we need to use adaptee with (our USB-C socket).

Methods to use the adapter sample in Swift?

You should utilize an adapter if you wish to combine a third-party library in your code, however it’s interface doesn’t match along with your necessities. For instance you may create a wrapper round a whole SDK or backend API endpoints so as to create a standard denominator. 👽

In my instance, I’m going to wrap an EKEvent object with an adapter class to implement a model new protocol. 📆

import Basis
import EventKit

// our goal protocol
protocol Occasion {
    var title: String { get }
    var startDate: String { get }
    var endDate: String { get }
}

// adapter (wrapper class)
class EventAdapter {

    non-public lazy var dateFormatter: DateFormatter = {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy. MM. dd. HH:mm"
        return dateFormatter
    }()

    non-public var occasion: EKEvent

    init(occasion: EKEvent) {
        self.occasion = occasion
    }
}

// precise adapter implementation
extension EventAdapter: Occasion {

    var title: String {
        return self.occasion.title
    }
    var startDate: String {
        return self.dateFormatter.string(from: occasion.startDate)
    }
    var endDate: String {
        return self.dateFormatter.string(from: occasion.endDate)
    }
}

// let's create an EKEvent adaptee occasion
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "MM/dd/yyyy HH:mm"

let calendarEvent = EKEvent(eventStore: EKEventStore())
calendarEvent.title = "Adapter tutorial deadline"
calendarEvent.startDate = dateFormatter.date(from: "07/30/2018 10:00")
calendarEvent.endDate = dateFormatter.date(from: "07/30/2018 11:00")

// now we will use the adapter class as an Occasion protocol, as a substitute of an EKEvent
let adapter = EventAdapter(occasion: calendarEvent)
// adapter.title
// adapter.startDate
// adapter.endDate

One other use case is when it’s a must to use a number of current remaining courses or structs however they lack some performance and also you need to construct a brand new goal interface on prime of them. Typically it’s a sensible choice to implement an wrapper to deal with this messy scenario. 🤷‍♂️

That’s all in regards to the adapter design sample. Often it’s very easy to implement it in Swift – or in every other programming language – however it’s tremendous helpful and typically unavoidable.

Youngsters, keep in mind: don’t go too exhausting on dongles! 😉 #himym