<!--
{
  "availability" : [
    "iOS: 17.0.0 -",
    "iPadOS: 17.0.0 -",
    "macCatalyst: 17.0.0 -",
    "macOS: 14.0.0 -",
    "swift: 5.9.0 -",
    "tvOS: 17.0.0 -",
    "visionOS: 1.0.0 -",
    "watchOS: 10.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "SwiftData",
  "identifier" : "/documentation/SwiftData/MigrationStage/custom(fromVersion:toVersion:willMigrate:didMigrate:)",
  "metadataVersion" : "0.1.0",
  "role" : "Case",
  "symbol" : {
    "kind" : "Case",
    "modules" : [
      "SwiftData"
    ],
    "preciseIdentifier" : "s:9SwiftData14MigrationStageO6customyAcA15VersionedSchema_pXp_AaE_pXpyAA12ModelContextCKcSgAHtcACmF"
  },
  "title" : "MigrationStage.custom(fromVersion:toVersion:willMigrate:didMigrate:)"
}
-->

# MigrationStage.custom(fromVersion:toVersion:willMigrate:didMigrate:)

```
@preconcurrency case custom(fromVersion: any VersionedSchema.Type, toVersion: any VersionedSchema.Type, willMigrate: (@Sendable (ModelContext) throws -> Void)?, didMigrate: (@Sendable (ModelContext) throws -> Void)?)
```

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)