storage-management-ref

Use URLResourceValues to query volumeAvailableCapacityForImportantUsage or volumeAvailableCapacityForOpportunisticUsage on the target storage location. These APIs return the available capacity for your use case, allowing you to decide whether to proceed with the write operation safely.

Purgeable files (isPurgeable) can be automatically deleted by iOS when storage is low; backup-excluded files (isExcludedFromBackup) are never synced to iCloud. Use purgeable for caches and temporary data; use backup exclusion for large files or regenerable content you don't want in backups.

Mark cache files as purgeable using URLResourceValues, store them in standard cache directories (Caches or Temporary), and check volumeAvailableCapacityForOpportunisticUsage before writes. iOS will purge these files first when space is needed, protecting user data.

Exclude large downloadable content, regenerable data, or temporary files that users can recreate. Set isExcludedFromBackup to reduce iCloud backup size and avoid unnecessary sync overhead for data that doesn't need cloud persistence.

Storage APIs and purge behavior are consistent across iOS, iPadOS, and macOS. However, Mac provides more storage and different user expectations; prioritize backup exclusion for large files and test capacity checks on each platform's typical disk constraints.