How to Write Decoupled Code

Decoupling code in Swift involves designing your classes, structs, and functions so that they have minimal dependencies on one another. This allows for more flexible, reusable, and testable code. Here are some techniques you can use to write decoupled code in Swift:

1. Dependency Injection: This is a technique in which an object receives its dependencies as constructor arguments, rather than creating them itself. This allows for easy substitution of mock objects during testing and makes it easy to switch from one implementation to another.
2. Protocol-Oriented Programming: In Swift, protocols define a blueprint of methods, properties, and other requirements that suit a particular task or piece of functionality. By using protocols, rather than concrete types, to define the interface of an object, you can decouple the implementation of the interface.
3. Single Responsibility Principle: Each class or struct should have a single responsibility, or a single reason to change. This makes it more likely that a change to one class or struct will not have ripple effects on other parts of the codebase.
4. Keep your classes small: When your classes contain a small number of lines of code, it makes it easy to understand, test, and maintain.
5. Keep your state immutability: Making your classes or structs immutable can make it much easier to reason about your code.
6. Break down large functions: Functions that are too big and complex should be broken down into smaller, simpler functions that each have a single responsibility. This makes the code more readable, testable, and easier to change.

Using these techniques, you can write more flexible, reusable, and testable code that is less likely to introduce bugs or cause unexpected behavior.