FAQ

availability() says NotAvailable on my iPhone. The iCloud entitlement is missing from the target, or the device has no iCloud account. Check Signing & Capabilities for iCloud with the container you pass, and Settings on the phone for a signed-in Apple Account.

Backups worked in Xcode builds and fail in TestFlight with Transport. CloudKit's Production environment has no schema until you deploy it. Xcode builds use Development, where record types are created on the fly. Open the CloudKit console, switch to Development, press "Deploy Schema Changes" and confirm. Once per record type change. See setup, iOS.

The simulator never finds iCloud. The simulator needs an iCloud login in its own Settings app. Without one, ICloudStorage and CloudKitStorage answer NotAvailable.

Android keeps asking for consent. NeedsConsent comes back whenever the grant is missing or revoked. Launch DriveConsent.request() from a user tap, not from a loop; see Android consent.

sync() answered RestorePending and uploaded nothing. The snapshot was marked empty and the cloud already holds a backup. This is the guard against a fresh install wiping a user's backup. Offer a restore; see restore.

Does Drive have a file size limit? Not from BackupKit. Files up to 5 MB go up in one multipart request; larger ones use Drive's resumable protocol in 8 MiB chunks, streamed from disk, and a dropped connection continues from the last chunk Drive acknowledged. The user's Drive quota is the only limit.

list() on iCloud Drive reports size == -1. The file is a placeholder that has not been downloaded to this device yet. prefetch(paths) before readBytes or downloadFile.

The user switched accounts. identityKey() changed, so the engine answers SourceChanged on resume and refuses to merge two accounts. Ask the user which one they meant.

Can I encrypt? Yes, before you hand bytes to the engine; hash the ciphertext. See recipes.

Does it run in the background? No. BackupKit does one sync per call. Bring your own scheduler.