Developing a Notes and To-Do Mobile Application
A notes app seems like "hello world" of mobile development. Actually, it has more nuances than most B2B products: conflict-free sync, rich-text editor, fast search across thousands of notes, lock screen widgets. Each is a separate technical challenge.
Local Storage: Room or Core Data
Android: Room with separate tables for notes, tags, tasks, attachments. iOS: Core Data or SwiftData (iOS 17+). SwiftData is simpler, but still young—for production with migrations, Core Data is more reliable.
Structure for combined notes + To-Do app:
@Entity data class Note(
@PrimaryKey val id: String = UUID.randomUUID().toString(),
val title: String,
val body: String, // plain text or Markdown
val isPinned: Boolean = false,
val color: Int? = null,
val updatedAt: Long = System.currentTimeMillis()
)
@Entity data class TodoItem(
@PrimaryKey val id: String = UUID.randomUUID().toString(),
val noteId: String?, // link to note if nested
val text: String,
val isDone: Boolean = false,
val dueDate: Long? = null,
val priority: Int = 0
)
FTS5 (Room) / NSPersistentContainer with NSFetchRequest and NSPredicate for search. On 10,000 notes, search must be instant.
Rich Text or Markdown
Key editor choice.
Plain text with Markdown rendering: simpler to implement, easier to sync (diff on lines). Render via Markwon (Android) or AttributedString with custom parser (iOS). Suits technical users.
Rich-text (WYSIWYG): Android—RichEditor or Quill.js in WebView; iOS—RichTextKit or custom UITextView with NSTextAttachment. Harder to build, but more familiar to mass audience.
Store content in format easy to diff—Markdown or JSON deltas (Quill Delta format).
Sync
For personal app without server—iCloud via CloudKit (iOS) or Google Drive API (Android/cross-platform). Both provide automatic sync without own backend.
For custom backend—CRDT (Conflict-free Replicated Data Types) or operational transforms. For notes, last-write-wins by updatedAt with explicit merge conflict shown to user often suffices.
Offline mandatory: all changes recorded locally, sync when connection returns via WorkManager / BGAppRefreshTask.
Widgets
Widget with recent notes or today's tasks on home screen—via WidgetKit (iOS 14+) / AppWidgetProvider (Android). Widget data from App Group (iOS) or ContentProvider (Android) so widget reads same DB.
iOS 16+: Lock Screen widgets via WidgetKit with systemSmall config.
Work Scope
- Local notes and tasks DB with tags
- Editor (plain text / Markdown / rich-text by choice)
- FTS search by content
- Sync (iCloud / Google Drive / custom backend)
- Home screen and lock screen widgets
- Reminders via
UserNotifications
Timeline
MVP: notes + to-do with local storage and search: 2–3 weeks. Full app with sync, widgets, rich-text editor: 6–8 weeks.