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Atomic Design Pattern in SwiftUI

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Atomic Design is a methodology for creating design systems with a clear, consistent hierarchy. It was introduced by Brad Frost and is inspired by chemistry. The core idea is to break down UI components into the smallest possible parts (atoms) and compose them to build more complex components and pages.

Atomic Design Hierarchy

1. Atoms

The basic building blocks of UI — buttons, labels, text fields, icons, colors, spacing units.
Example: PrimaryButton, AppText, Icon

2. Molecules

Groupings of atoms that form simple components.
Example: SearchBar = TextField + Icon, LabeledSwitch

3. Organisms

Relatively complex, standalone components made of atoms and molecules.
Example: LoginForm, UserCard, HeaderView

4. Templates

Layouts or skeletons that define the structure of pages using organisms.
Example: AuthScreenTemplate, DashboardTemplate

5. Pages

Final screens with real data/content, composed of templates.
Example: LoginScreen, SettingsScreen.

Here is how an example folders structure looks like in iOS app powered by SwiftUI. 

MySwiftUIApp/

│

├── Resources/                 // Assets, Localization, etc.

│   ├── Assets.xcassets

│   ├── Localizable.strings

│   └── Colors.swift

│

├── App/                       // Entry point and configuration

│   ├── MySwiftUIAppApp.swift

│   └── AppRouter.swift

│

├── Core/                      // Shared reusable logic

│   ├── Network/

│   ├── Extensions/

│   ├── Utils/

│   └── Models/

│

├── DesignSystem/              // Atomic Design Pattern folder

│   ├── Atoms/                 // Basic UI elements

│   │   ├── PrimaryButton.swift

│   │   ├── AppText.swift

│   │   ├── Icon.swift

│   │   └── Spacing.swift

│   │

│   ├── Molecules/             // Small component combinations

│   │   ├── TextFieldWithIcon.swift

│   │   ├── LabeledSwitch.swift

│   │   └── ProfileImageWithName.swift

│   │

│   ├── Organisms/             // Large UI blocks

│   │   ├── LoginForm.swift

│   │   ├── UserProfileSection.swift

│   │   └── ProductCard.swift

│   │

│   ├── Templates/             // Layout structures with placeholder content

│   │   ├── AuthScreenTemplate.swift

│   │   ├── FeedPageTemplate.swift

│   │   └── SettingsPageTemplate.swift

│   │

│   └── Pages/                 // Final UI Screens

│       ├── LoginScreen.swift

│       ├── HomeScreen.swift

│       └── SettingsScreen.swift

│

├── ViewModels/                // All SwiftUI ViewModels (MVVM)

│   ├── LoginViewModel.swift

│   ├── HomeViewModel.swift

│   └── SettingsViewModel.swift

│

└── Tests/                     // Unit and UI Tests

    ├── MySwiftUIAppTests/

    └── MySwiftUIAppUITests/

 

Advantages:

  • Reusability: Components are small and self-contained, encouraging reuse.
  • Consistency: Promotes a unified design language across your app.
  • Scalability: Easily scale design systems by combining existing components.
  • Testability: Smaller atomic components are easier to unit test.
  • Clear Structure: Developers and designers have a shared, understandable component hierarchy.
  • Collaboration Friendly: Makes handoff between design and development smoother.

Limitations:

  • Overhead for Small Projects: May feel too heavy for very simple apps or MVPs.
  • Naming Complexity: Distinguishing between molecules, organisms, templates can become ambiguous.
  • Learning Curve: Developers unfamiliar with the pattern might find the structure over-engineered.
  • Increased Boilerplate: Can lead to many files and folders, even for small features.
  • Not Always a Natural Fit: Sometimes, trying to "force" components into the hierarchy doesn't make sense.
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