Cloudkit Sync

Covers CloudKit from container setup through CKSyncEngine, with SwiftData integration, query predicates, subscriptions, and conflict resolution. Use it when you're adding iCloud sync to an app, debugging CKError.serverRecordChanged conflicts, or reviewing whether encrypted fields break queries. The guide is thorough on what NSPredicate operators actually work, when custom zones are required, and how CKSyncEngine handles automatic retries but still punts conflict resolution back to you. Targets iOS 26+ with Swift 6.3, though most patterns apply to earlier versions. Good reference if you're past the "enable CloudKit capability" stage and need to understand zone subscriptions, shared database mechanics, or why your CONTAINS predicate isn't firing.