iOS Inside #004 – iOS App Architecture in 2025: From Chaos to Clean, with Purpose

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You’ve probably heard of MVC, MVVM, Clean Architecture, VIPER, TCA, Redux…
And maybe you’ve tried applying one of them to your project — and got frustrated halfway through.

The truth is, as iOS devs, we’re often stuck between the code that needs to work today and the architecture that promises to save tomorrow.

This article is about bridging that gap.

It’s not about which pattern is “the best.”
It’s about understanding what really matters when structuring an iOS app in 2025.
And more importantly: how to do it realistically, with purpose, and without falling into the trap of architectural purism.

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Why talk about architecture now?

Because apps are getting more complex.
Because Swift has evolved.
And because Xcode won’t save you from a 800-line ViewController.

Architecture matters when:

• Your team grows

• Your code needs to last

• Features start to cross paths

• Maintenance becomes a nightmare

• Onboarding takes too long

But maybe most importantly:
It matters when you want peace of mind 6 months from now.

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The current landscape: what’s actually being used?

If you open 10 iOS codebases today, you’ll likely find:

• A bit of MVC (with bloated ViewControllers)

• A mix of MVVM (with Combine or plain closures)

• Some flavor of Clean Architecture

• A growing adoption of TCA (The Composable Architecture)

Most projects today are in a gray zone — not fully chaotic, not strictly structured. And that’s okay.

The real question is:
How do we make it work well?

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Architectures you’ll encounter (and what to do with them)

Let’s be clear: no architecture is perfect.
Each solves certain problems — and brings trade-offs.

MVC (Model-View-Controller)

Pros:

• Simple to implement

• Great for prototypes or small apps

• Works well with Storyboards and UIKit

Cons:

• Everything ends up in the ViewController

• Hard to test

• Logic is scattered and tightly coupled

Use it for fast iteration. But extract responsibilities early to avoid the trap.

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MVVM (Model-View-ViewModel)

Pros:

• Separates presentation logic from the View

• Works great with SwiftUI or Combine

• Enables reuse of logic across views

Cons:

• ViewModels often become bloated

• Confusion around what goes where

• Can become a different kind of mess

MVVM shines when used with discipline and clean bindings.

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Clean Architecture

Pros:

• Clear separation of concerns

• Makes testing and scaling easier

• Encourages maintainable, modular code

Cons:

• More setup and ceremony

• Requires understanding boundaries and use cases

• Can be overkill for small projects

Perfect for long-term projects, cross-platform code, and growing teams.

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TCA (The Composable Architecture)

Pros:

• Highly testable

• Scales well across large apps

• Promotes composition and clear state management

Cons:

• Steep learning curve

• Verbose for small features

• Hard to onboard newcomers

Great when you need predictable, scalable, and testable state management.

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VIP / VIPER

Pros:

• Strong separation of layers

• Ideal for legacy or large enterprise apps

• Predictable flow and unit testing

Cons:

• Too verbose

• Lots of boilerplate

• Slow to evolve

Still valid in massive apps — otherwise, not so much.

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Choosing with purpose: not just because someone said so

Before picking any architecture, ask this:

What am I trying to solve?

Architecture should be a response to a problem, not just a trend.

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If you need testability:

Use Clean Architecture, TCA, or a clean MVVM setup.
Focus on separating business logic from UI and injecting dependencies.

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If you need scalability:

Modularize by Feature or Domain, isolate concerns, and define clear boundaries.

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If you need speed:

Use MVC with good folder structure or light MVVM.
Avoid overengineering. Focus on shipping.

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If your team is small or junior:

Avoid patterns with steep learning curves.
Clarity > Complexity.

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If you're working across platforms:

Separate business logic entirely from the UI layer.
Clean Architecture with a pure domain layer is your friend.

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Modularization: break it down, cleanly

Ways to modularize:

1. By Layer (Core, UI, Networking)

2. By Domain (Auth, Profile, Feed)

3. By Feature (HomeFeature, SettingsFeature) using Swift Packages

Start simple. Extract common components. Separate networking. Then evolve to packages.

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Example: from ViewController chaos to clean structure

The “before” (classic bloat):

class LoginViewController: UIViewController {
    @IBAction func loginTapped() {
        // UI, logic, networking, parsing all here
    }
}

The “after” (clean structure):

• LoginViewController: handles UI only

• LoginViewModel: orchestrates logic

• LoginUseCase: defines what to do

• AuthService: makes the actual request

Now each layer is testable, clear, and independent.

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How to apply this today

1. Start by organizing your folders by context

2. Extract shared logic into a Core or Shared module

3. Refactor small parts incrementally

4. Choose a style based on your actual needs, not trends

5. Align your team’s understanding — architecture is culture

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Final thoughts

The best architecture is the one your team understands, maintains, and evolves.

It doesn’t have to be pure.
It just has to be clear.

Next episode?
We’ll talk about async testing, snapshot previews, and patterns to scale code across teams and platforms.

Until then:
Build. Run. Refactor. With purpose.