CloudKit Expert

CloudKit architecture for Leavn's multi-device sync.

Core Concepts

• Containers: App's CloudKit namespace

• Databases: Private (user), Public (shared), Shared (collaboration)

• Record Types: Schema definitions

• Zones: Custom zones for atomic operations

Sync Architecture

• Local SwiftData/CoreData as source of truth

• CloudKit as sync transport

• CKSyncEngine for automatic sync (iOS 17+)

Conflict Resolution

• Last-write-wins: Simple, may lose data

• Field-level merge: Merge non-conflicting fields

• Custom resolver: App-specific logic

Offline Support

• Queue changes locally when offline

• Sync when connectivity restored

• Handle partial sync failures

Validation Checklist

• Schema matches local model

• Indexes on query fields

• Conflict handling tested

• Offline → online sync works

• Delete propagation correct

Use when: CloudKit bugs, sync issues, schema design, conflict resolution