Three common architectures for modern iOS apps are: MVVM, TCA, and VIPER. This post will talk about using MVVM and TCA for our spec TaskManager app. By Jp.
The TaskManager app leverages MVVM and TCA to handle its three modules (Task, Text, Setting) with consistent functionality.
MVVM Architecture
- Core Concept: ViewModel acts as an intermediary between Model data and SwiftUI views
- TagView Example: A TagView uses a @Observable ViewModel to manage edit mode (active/inactive) and text conversion via convertTagIfValid. The view binds directly to the ViewModel’s state, updating dynamically when user input changes
- Navigation & Data Flow: Master-detail views (e.g., Task list with detail editing) share a central ViewModel. User interactions in child views update parent data through well-defined protocols and business logic encapsulated in the ViewModel
TCA Architecture
- Core Concept: Unidirectional data flow—State → Actions → Reducers ensures immutable state changes driven by explicit user actions
- Task Management Example: A task array is stored in State, manipulated via actions like addButtonTapped, deleteSent, or editTask. Reducers handle all business logic (e.g., validating input before saving), returning new States through effects if needed
- Navigation: Uses destination states to transition between features (e.g., opening an Add/Edit form as a sheet). Actions are strictly defined, and reducers process them immutably to update State
Benefits & Limitations
- MVVM Advantages: Simplified state management via ViewModels; flexible UI updates without heavy boilerplate
- TCA Advantages: Predictable flow, easier testing due to immutable States, and clear separation of concerns (Reducers for logic)
- Challenges in TCA: Increased complexity with deep nested views requiring destination coordination. MVVM’s loose coupling can lead to scattered business logic if not structured carefully
Both architectures achieve consistent functionality across modules but differ in their approach to state management. MVVM prioritizes rapid UI updates via ViewModels, while TCA emphasizes strict flow control for predictability. The choice depends on team familiarity and project complexity—MVVM suits flexible UIs, whereas TCA excels at complex navigation patterns and data integrity. Good read!
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