Null Object - Swift

The Null Object pattern provides a substitute for a null reference or nil value, allowing you to avoid null checks throughout your code. Instead of checking for nil, you call a method on the null object, which performs a no-op or returns a default value. This simplifies code and reduces the risk of NullPointerExceptions (or similar errors in Swift).

The Swift implementation uses a protocol to define the interface that both the real object and the null object conform to. The NullProduct class conforms to the Product protocol, providing empty or default implementations for all required methods. This allows it to be used anywhere a Product is expected without causing errors. Swift’s protocol-oriented programming style makes this a natural fit, promoting flexibility and avoiding conditional unwrapping.

protocol Product {
    func use()
    func getName() -> String
}

class RealProduct: Product {
    private let name: String

    init(name: String) {
        self.name = name
    }

    func use() {
        print("Using \(name)")
    }

    func getName() -> String {
        return name
    }
}

class NullProduct: Product {
    func use() {
        // Do nothing
    }

    func getName() -> String {
        return "No Product"
    }
}

func processProduct(product: Product) {
    product.use()
    print("Product name: \(product.getName())")
}

// Example Usage
let product1: Product = RealProduct(name: "Laptop")
let product2: Product = NullProduct()

processProduct(product: product1)
processProduct(product: product2)