As software projects grow, so does their complexity. Managing this complexity is one of the most critical aspects of software development. One way of handling this complexity is through the principle of modularisation. In this post, we’ll delve deeper into the concept of modularisation and its counterpart, dependencies, in the context of iOS development with Swift.

Modularisation in iOS

In its essence, modularisation is the process of dividing a software system into separate, independent modules. Each module encapsulates a specific part of the system’s functionality and exposes a well-defined interface that other modules can use.

In the context of iOS development, an application could be broken down into various modules like the User Interface (UI), Business Logic, Data Access, and Utilities. Each module would have a specific role and would interact with other modules as necessary through their exposed interfaces. This kind of separation promotes code reuse and separation of concerns, making your iOS application easier to develop, maintain, and scale.

In Swift, you can create modules by using Libraries, Frameworks, Swift Packages, Pods etc. A module can encapsulate reusable code (like a networking layer), a set of related features (like user profile management), or a complete functionality slice of your application (like an ordering system in an e-commerce app).

Understanding Dependencies

A dependency exists when one module relies on another to function. In our iOS application example, a UI module might depend on a Business Logic module to provide the data it needs to display. This is a typical instance of a vertical dependency: a higher-level module (like UI) depending on a lower-level module (like Business Logic).

On the other hand, horizontal dependencies occur between modules at the same level of abstraction. For instance, two different UI modules might depend on a shared UI Components module for reusable UI elements.

Understanding dependencies between your iOS app’s modules is crucial for effective architecture design. However, improperly managed dependencies can lead to issues like tight coupling, making your app hard to maintain, extend, and test.

Dependency Graphs in Swift

To manage dependencies effectively, we need a clear understanding of how they interact. This is where dependency graphs come in. In a dependency graph, each node represents a module in your Swift project, and each edge signifies a dependency.

Consider an iOS application composed of four modules: Authentication, Profile, ShoppingCart, and Products. If ShoppingCart depends on Profile and Products, and Profile depends on Authentication, the dependency graph would look something like this:

ShoppingCart --> Profile --> Authentication
               --> Products

Dependency graphs are valuable tools in identifying which modules are most dependent, which are most depended upon, and spotting potential problem areas, such as circular dependencies.

Strategies for Effective Dependency Management in Swift

Poorly managed dependencies can lead to a rigid, tightly-coupled system, making it tough to maintain, extend, and test your iOS application. Below are some strategies and techniques to manage dependencies effectively in Swift:

Minimizing Dependencies

Minimizing the number of dependencies a module has leads to a loosely coupled system. The fewer dependencies a module has, the more independent it is. This independence makes the module more manageable, testable, and less affected by system-wide changes.

Dependency Injection

Dependency Injection (DI) is a strategy where a module’s dependencies are provided (injected), rather than the module creating or locating its dependencies. DI promotes loose coupling, making your Swift modules easier to test and maintain.

There are various ways to implement DI in Swift, like Initializer Injection, Property Injection, or Method Injection. You can choose the method that best suits your needs.

Swift Package Manager

Swift Package Manager (SPM) is a tool for managing the distribution of Swift code, making it easy to create and manage Swift packages. SPM is integrated with the Swift build system to automate the process of downloading, compiling, and linking dependencies.

Using Facade Pattern

Facade Pattern provides a simplified interface to a complex subsystem. It’s a way to help decouple a client from a subsystem of components. In Swift, you can use protocols to define a simplified interface to a set of functionalities in a module.

Avoiding Circular Dependencies

Circular dependencies occur when two or more modules depend on each other, either directly or indirectly. These dependencies can create infinite loops, making your app prone to crashes and making the modules hard to test independently. Be aware of this when creating your dependency graphs.


Managing complexity in large Swift projects can be a daunting task, but with modularization and effective dependency management, it becomes a lot more feasible.

Remember, no single method works best for every scenario. Therefore, understanding your application’s needs and experimenting with different strategies will ultimately lead to the most effective architecture design.