Hands-On Design Patterns with Swift

Anatomy of the bridge pattern

The bridge pattern is oriented around two interfaces:

• Abstraction
• Implementor

Instead of implementing the Abstraction interface directly, the bridge pattern encourages the introduction of the Implementor interface, which in turn will be the top-level interface for feature implementation.

Let's consider the following code. It shows a class that performs some work:

class Abstraction {    func start()    func stop()}

If we want to be able to swap the implementation of start() or stop() with other implementations, it's quite complicated. We could leverage subclassing, but it may be inconvenient, as it forces us to refactor our entire program.

The bridge pattern can help us with this problem. First, let's extract the ...