Solving Common Problems with the Strategy Design Pattern in Swift

The Strategy Design Pattern is a behavioral design pattern that is used to define a family of algorithms, encapsulate each one as an object, and make them interchangeable. This pattern allows for algorithms to be easily swapped in and out, making it easy to modify the behavior of an object at runtime.

One example of where the Strategy Design Pattern could be useful is in a payment system. Let's say that you have a payment system that can accept payments from different sources, such as credit cards, PayPal, and Venmo. Each payment source has its own unique algorithm for processing the payment, and you want to be able to easily swap out one payment source for another.

With the Strategy Design Pattern, you could create a PaymentStrategy protocol that defines the methods that each payment algorithm must implement.

​Then, you could create classes for each payment source, such as CreditCardPaymentStrategy, PayPalPaymentStrategy, and VenmoPaymentStrategy, that conform to the PaymentStrategy protocol and implement the required methods.

When it's time to process a payment, you can create an instance of the appropriate payment strategy and pass it to the payment system. The payment system can then use the payment strategy to process the payment without needing to know the details of the specific payment algorithm being used. This makes it easy to swap out one payment source for another without having to change the code of the payment system itself.

Here is an example of how the Strategy Design Pattern could be implemented in Swift to process payments from different sources:

​​The Strategy Design Pattern is a useful tool for defining a family of algorithms and making them interchangeable. By using this pattern, you can easily modify the behavior of an object at runtime and make your code more flexible and adaptable.