Overview
SnapInventory is a simple inventory app for small retail stores. It tracks items, photos, quantities, and basic sync across devices. This article teaches a milestone-driven plan. You will get an MVP feature list. You will get screens, models, API contracts, and build order. Each milestone explains what to build first, why it matters, and common mistakes to avoid.
MVP Features
- Item CRUD: create, read, update, delete items with photo and barcode.
- Inventory Count: adjust quantities and view stock levels.
- Search & Filter: quick lookup by name or barcode.
- Offline Local Storage: work without network and persist changes.
- Optional Sync: basic push/pull sync with a server to keep devices in sync.
- Export: CSV export for bookkeeping.
Screens
- Inventory List: searchable list of items with thumbnails and quantities.
- Item Detail: full item view with photo, barcode, quantity change controls, and notes.
- Add / Edit Item: camera/photo import, barcode scanner, name, SKU, quantity.
- Count Mode: fast mode to adjust quantities for stocktakes.
- Settings: sync toggle, export button, and local backup.
Data Models
Keep the model small. Use a single Item entity for MVP.
import Foundation
import SwiftUI
struct Item: Identifiable, Codable {
var id: UUID
var name: String
var sku: String?
var barcode: String?
var quantity: Int
var photoFileName: String?
var updatedAt: Date
}
Store photos as files. Store model objects in local persistent store. Add a simple changeLog field for sync conflict resolution if you implement sync.
API Contracts (Optional Sync)
Design a minimal REST API for MVP. Keep endpoints simple.
POST /sync/push
Request: { deviceId, items: [Item] }
Response: { accepted: [id], conflicts: [id] }
GET /sync/pull?since=TIMESTAMP
Response: { items: [Item] }
Use simple last-write-wins with updatedAt for the first iteration. Add a conflict endpoint if you need user resolution later.
Milestones
Split development into three milestones. Each milestone targets a shippable subset. Build and test each milestone before moving on.
Milestone 1: Local CRUD and Photo Support
What to build first
- Local storage layer for items.
- Inventory List screen with add and delete.
- Add/Edit Item screen with camera and photo picker.
Why it matters
- Local CRUD gives core value. Users can record stock without network.
- Photos make items identifiable. They reduce errors.
Common mistakes to avoid
- Saving images directly in the database. Save files and store references.
- Making the data layer tightly coupled to the UI. Keep storage behind a repository API.
- Neglecting simple validation. Prevent empty names and negative quantities.
Example: simple repository protocol
protocol ItemRepository {
func fetchAll() async throws -> [Item]
func create(_ item: Item) async throws
func update(_ item: Item) async throws
func delete(id: UUID) async throws
}
Milestone 2: Fast Counting Mode and CSV Export
What to build first
- Count Mode screen optimized for quick increments and decrements.
- Batch update support in the repository.
- CSV export that converts items to a downloadable file.
Why it matters
- Counting mode is a high-frequency task for store staff. Good UX here reduces time spent.
- CSV export solves one immediate business need. Accountants and owners use it.
Common mistakes to avoid
- Building the count UI like a normal list. Use large tappable areas and fast feedback.
- Applying CSV export to in-memory objects only. Export from the persisted store to avoid stale data.
- Blocking the main thread during batch operations. Use background tasks and show progress.
Example: batch update sketch
func applyBatchUpdates(_ updates: [(UUID, Int)]) async throws {
// updates: [(itemId, newQuantity)]
for (id, qty) in updates {
var item = try await repository.fetch(id)
item.quantity = qty
try await repository.update(item)
}
}
Milestone 3: Optional Sync and Conflict Handling
What to build first
- Pull-only sync to start. Fetch server items and merge into local store.
- Push sync with a small change queue for offline edits.
- Conflict strategy: basic last-write-wins using updatedAt timestamp and UI for manual resolve if needed.
Why it matters
- Sync unlocks multi-device use and backups. It increases app usefulness.
- Starting with pull-first limits accidental overwrites.
Common mistakes to avoid
- Trying to build complex sync and conflict resolution in one go. Start simple and observe real conflicts.
- Sending full object blobs every sync. Send deltas when possible to save bandwidth.
- Not writing automated tests around merge logic. Test merge cases before shipping.
Example: basic sync client using URLSession
struct SyncClient {
let baseURL: URL
func pull(since: Date?) async throws -> [Item] {
var url = baseURL.appendingPathComponent("/sync/pull")
if let since = since {
url = URL(string: "\(url)?since=\(Int(since.timeIntervalSince1970))")!
}
let (data, _) = try await URLSession.shared.data(from: url)
return try JSONDecoder().decode([Item].self, from: data)
}
}
Testing and Risk Management
Manage risk with rapid tests and staged releases.
- Unit tests for repository and sync logic.
- UI tests for add, edit, and count flows.
- Manual scenarios for offline edits and conflict cases.
- Telemetry for sync failures and storage errors.
Start with a small beta group for real-world feedback. Use crash reporting and simple logs to track issues.
Roadmap Summary and Next Steps
Follow the milestones in order. Complete local CRUD, then add fast counting and export. Add sync last. Keep interfaces small. Keep the sync protocol minimal at first. Build tests around the storage and merge logic early. Iterate on UX for counting and photo handling. Ship a focused MVP and collect user feedback. Use feedback to expand conflict resolution and advanced reports.
This roadmap gives you a clear path. Break each milestone into 1 to 2 week sprints. Keep scope tight. Track bugs and usage data. You will get to a usable product fast.