Habit Rabbit

Habit Rabbit is a SwiftUI demo project showcasing modern iOS development patterns. I open-sourced this repository to highlight my approach to SwiftUI architecture, SwiftData integration, and custom UI design.

Architecture & State Management

The app avoids massive views by keeping domain logic decoupled and utilizing the @Observable macro alongside Swift's Environment.

• Explicit Dependency Injection:

  Rather than relying solely on SwiftUI's implicit data flow, the ModelContainer is explicitly initialized at the app root (HabitRabbit.swift). Its mainContext is safely passed into a central Dashboard.Manager, which is then injected into the view hierarchy via .environment().

• Manager Lifecycle & View Model Caching:

  To prevent performance degradation and state resets in dynamic grids, the app does not blindly recreate view models. The Dashboard.Manager acts as a factory, maintaining a [PersistentIdentifier: Habit.Card.Manager] cache. This maps SwiftData models to stable, long-living @Observable card managers, ensuring fluid redraws and strict separation of concerns.

• Reusable Forms & Focus Management:

  Data entry is handled by a highly reusable Dashboard.Sheet component that drives both the "Add" and "Edit" workflows via an InitialValues struct. The form includes production-level UX details, such as programmatic keyboard focus management (FocusState) to smoothly advance users through the input fields.

Data Persistence with SwiftData

SwiftData is used to handle data persistence efficiently and maintain a smooth scrolling experience, even as historical data grows:

• Relational Models:

  The schema separates the Habit definition from its historical Habit.Value entries, utilizing cascade delete rules to maintain data integrity.

• Caching & Prefetching (Card Level):

  The Card.Manager implements a local dictionary cache to prefetch active rolling windows (e.g., a 30-day core with 14-day buffers). This allows for smooth pagination through dates without constantly hitting the persistent store.

• Cursor-Based Pagination (Detail Level):

  To ensure memory safety for habits with years of history, the DetailView.Manager implements cursor-based pagination. Using fetchOffset and fetchLimit, it loads historical records in discrete chunks (100 at a time) only when requested by the user.

UI Styling & Animations

The interface features custom components and uses modern SwiftUI transition APIs to create a responsive, fluid feel:

• Modern View Transitions:

  Layout morphing—such as switching a card between daily, weekly, and monthly views—is handled seamlessly using .geometryGroup() and .matchedGeometryEffect(). Furthermore, navigating to the Detail View utilizes the modern .navigationTransition(.zoom(sourceID:)) API for continuous, fluid hero animations.

UI Styling & Animations

The interface has custom components and uses modern SwiftUI transition APIs to create a responsive feel:

• View Transitions:

  Layout morphing like switching a card between daily, weekly, and monthly views is handled seamlessly using .geometryGroup(), .matchedGeometryEffect(), and .transition(.blurReplace).

screenshot.-.1.mov

• Custom Components:

  The custom ProgressBar includes a math function that applies a power curve to adjust mid-range values, visually offsetting the shortening caused by SwiftUI's rounded capsule caps. Additionally, the monthly view dynamically calculates column indexes to align data to the correct weekdays on the fly.

• Context-Aware Theming:

  Visual elements adjust based on both the environment (light/dark mode) and the data state. For example, completing a target modifies the brightness and border width depending on whether the app is in dark mode or if the habit is considered a "good" or "bad" habit.

• Micro-Interactions:

  Numeric labels use .monospacedDigit() and .contentTransition(.numericText()) for clean tick-ups when logging data. Relevant data triggers are also tied to haptic feedback via .sensoryFeedback.

Navigating the Codebase

To review how these concepts are implemented, here are a few recommended starting points:

• /App/Models/Habit.swift & Value.swift**: SwiftData models and fetch descriptors.
• /Views/Card/Manager/Card.Manager.valueOperations.swift: Data caching, prefetching, and fetching logic.
• /Views/Other/ProgressBar/ProgressBar.geometry.swift: The math logic used for the progress bar curvature correction.
• /Views/Dashboard/Dashboard.swift: The root view demonstrating dependency injection and the main grid layout.