Swift Design Patterns: Bridge – Connecting Interfaces & Implementations
Design patterns are an essential part of software engineering. They are reusable solutions to commonly occurring problems in software development. In this article, we will be discussing the Bridge design pattern in Swift.
The Bridge design pattern is used to separate an interface from its implementation. This allows us to decouple the two components and make them independent of each other. This also makes it easier to modify or extend either component without affecting the other.
Let’s look at an example to understand the concept better. Let’s say we are building a mobile app for a restaurant. We have two classes, one for the menu items and another for the order. The menu items class is responsible for displaying the items on the menu while the order class is responsible for placing the orders.
The menu items class has an interface which is responsible for displaying the items on the menu. The order class also has an interface which is responsible for placing the orders. We can use the Bridge design pattern to decouple these two interfaces.
We can create a bridge class which contains both the menu items interface and the order interface. This bridge class can be used to connect the two components. Now, when a user selects an item from the menu, the bridge class will send the order to the order class. Similarly, when the order is placed, the bridge class will update the menu items interface with the new order.
Now let’s look at how we can implement this in Swift. We will create two protocols for the menu items interface and the order interface.
// Menu Items Protocol
protocol MenuItemsInterface {
func displayMenuItems()
}
// Order Protocol
protocol OrderInterface {
func placeOrder()
}
We will also create a class which conforms to both protocols. This class will act as the bridge between the two components.
class BridgeClass: MenuItemsInterface, OrderInterface {
private var menuItems: [String]
private var order: [String]
// MARK: - MenuItemsInterface
func displayMenuItems() {
for item in menuItems {
print(item)
}
}
// MARK: - OrderInterface
func placeOrder() {
for item in order {
print("Order placed for \(item)")
}
}
}
Now, we can use the bridge class to connect the menu items interface and the order interface. When a user selects an item from the menu, the bridge class will send the order to the order class and update the menu items interface with the new order.
The Bridge design pattern is a great way to decouple the interface from its implementation. This makes it easier to modify or extend either component without affecting the other. It also makes it easier to test and maintain the code. I hope this article helped you understand the concept of the Bridge design pattern in Swift.