/appmigrationkit

name: appmigrationkit
description: "Transfer app data to or from other platforms using AppMigrationKit. Use when implementing system-orchestrated one-time migration between iOS and Android or another platform, building an AppMigrationExtension, packaging transportable resources with ResourcesArchiver, importing resources on the destination device, reporting import progress, handling migration errors and app group cleanup, checking MigrationStatus, or testing migration code with AppMigrationTester."

AppMigrationKit

One-time cross-platform data transfer for app resources. Enables apps to export data to or import data from another platform (for example, Android) during device setup or onboarding. AppMigrationKit APIs are iOS 26.0+ / iPadOS 26.0+; the data-container entitlement is iOS 26.1+ / iPadOS 26.1+ / Mac Catalyst 26.1+. Swift 6.3.

> **Beta-sensitive.** AppMigrationKit is new in iOS 26 and may change before GM. > Re-check current Apple documentation before relying on specific API details.

AppMigrationKit uses an app extension model. The system orchestrates the transfer between devices. The app provides an extension conforming to export and import protocols, and the system calls that extension at the appropriate time. The app itself never manages the network connection between devices.

Contents

• [Architecture Overview](#architecture-overview)
• [Setup and Entitlements](#setup-and-entitlements)
• [App Migration Extension](#app-migration-extension)
• [Exporting Resources](#exporting-resources)
• [Importing Resources](#importing-resources)
• [Migration Status](#migration-status)
• [Progress Tracking](#progress-tracking)
• [Testing](#testing)
• [Common Mistakes](#common-mistakes)
• [Review Checklist](#review-checklist)
• [References](#references)

Architecture Overview

AppMigrationKit operates through three layers:

1. **App extension** -- An `AppMigrationExtension` conforming type that the system invokes during migration. It handles data export and import. 2. **System orchestration** -- The OS manages the device-to-device session, transport, and scheduling. The extension does not control when it runs. 3. **Containing app** -- After migration completes, the app checks `MigrationStatus.importStatus` on first launch to determine whether migration occurred and whether it succeeded.

Key types:

| Type | Role | |---|---| | `AppMigrationExtension` | Protocol for the app extension entry point | | `ResourcesExportingWithOptions` | Protocol for exporting files via archiver | | `ResourcesExporting` | Simplified export protocol (no custom options) | | `ResourcesImporting` | Protocol for importing files on the destination | | `ResourcesArchiver` | Streams files into the export archive | | `MigrationDataContainer` | Access to the containing app's data directories | | `MigrationStatus` | Check import result from the containing app | | `MigrationPlatform` | Identifies the other device's platform (e.g., `.android`) | | `MigrationAppIdentifier` | Identifies the source app by store and bundle ID | | `AppMigrationTester` | Test-only actor for validating export/import logic |

Setup and Entitlements

Entitlement

The app extension requires the `com.apple.developer.app-migration.data-container-access` entitlement. Its value is a single-element string array containing the bundle identifier of the containing app:

<key>com.apple.developer.app-migration.data-container-access</key>
<array>
    <string>com.example.myapp</string>
</array>

No other values are valid. This entitlement grants the extension read access to the containing app's data container during export and write access during import. The entitlement itself is available on iOS 26.1+, iPadOS 26.1+, and Mac Catalyst 26.1+, even though the core AppMigrationKit APIs are available on iOS 26.0+ and iPadOS 26.0+.

Extension Target

Add a new App Extension target to the Xcode project. The extension conforms to one or more of the migration protocols (`ResourcesExportingWithOptions`, `ResourcesExporting`, `ResourcesImporting`).

App Migration Extension

The extension entry point conforms to `AppMigrationExtension`. During migration, the system prevents launching the containing app and its other extensions to ensure exclusive data access.

Accessing the Data Container

The extension accesses the containing app's files through `appContainer`:

import AppMigrationKit

struct MyMigrationExtension: ResourcesExporting {
    var resourcesSizeEstimate: Int { estimateTotalExportSize() }
    var resourcesVersion: String { "1.0" }
    var resourcesCompressible: Bool { true }

    func exportResources(
        to archiver: sending ResourcesArchiver,
        request: MigrationRequest
    ) async throws {
        let container = appContainer

        // container.bundleIdentifier     -- app's bundle ID
        // container.containerRootDirectory -- root of the app container
        // container.documentsDirectory    -- Documents/
        // container.applicationSupportDirectory -- Application Support/
    }
}

`MigrationDataContainer` provides `containerRootDirectory`, `documentsDirectory`, and `applicationSupportDirectory` as `URL` values pointing into the containing app's sandbox.

Exporting Resources

Conform to `ResourcesExportingWithOptions` (or `ResourcesExporting` for no custom options) to package files for transfer. The system calls `exportResources(to:request:)` with a `ResourcesArchiver` and a `MigrationRequestWithOptions`.

Declaring Export Properties

struct MyMigrationExtension: ResourcesExportingWithOptions {
    typealias OptionsType = MigrationDefaultSupportedOptions

    var resourcesSizeEstimate: Int {
        // Return estimated total bytes of exported data
        calculateExportSize()
    }

    var resourcesVersion: String {
        "1.0"
    }

    var resourcesCompressible: Bool {
        true  // Let the system compress during transport
    }
}

• `resour