Facade

Provides a simplified interface to a complex subsystem, hiding its internals.

The Problem

A complex library or set of services has many classes, configurations, and entry points. Client code becomes tangled managing all of them directly.

How It Works

›Reduces coupling between client and complex subsystem
›Doesn't seal the subsystem — advanced users can bypass the facade when needed
›Single entry point makes the subsystem easier to use correctly
›Simplifies testing — you can mock the facade instead of every subsystem class
›Common when wrapping third-party SDKs to limit exposure to your app

When to Use

✓Simplifying a complex library or set of services behind one clean interface

✓Layering subsystems to reduce dependencies between them

✓Providing sensible defaults for the common case

✓Wrapping a third-party SDK so your app is not tightly coupled to it

Real-World Examples

🍎

iOS

Alamofire (facade over URLSession stack), AVPlayer wrapper classes

🤖

Android

Glide/Picasso (facade over Bitmap/network ops), Retrofit

🌐

Web

jQuery (facade over DOM APIs), axios (facade over XMLHttpRequest/fetch)

Code Examples

Swift

// Complex subsystems
class AuthService {
    func login(user: String, pass: String) -> String { "token_abc" }
}
class ProfileService {
    func fetch(token: String) -> [String: String] { ["name": "Agus"] }
}
class CacheService {
    func store(_ key: String, _ value: Any) { }
}

// Facade: one entry point for the whole auth + profile flow
class AppFacade {
    private let auth    = AuthService()
    private let profile = ProfileService()
    private let cache   = CacheService()

    func signIn(username: String, password: String) -> [String: String] {
        let token   = auth.login(user: username, pass: password)
        let data    = profile.fetch(token: token)
        cache.store("profile", data)
        return data
    }
}

// Client only deals with one object
let app = AppFacade()
print(app.signIn(username: "agus", password: "secret"))
// ["name": "Agus"]