> ## Documentation Index
> Fetch the complete documentation index at: https://docs.linkrunner.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Collecting Device Data

> Where each device_data field comes from on iOS, and what attribution loses without it.

`device_data` is the object you send on `init`, `attribution-data`, and `signup`. It carries the signals Linkrunner uses to match an install to a click. On iOS, every field comes from an Apple framework, so you need no third-party libraries.

The [full client](/sdk-less/ios-quickstart) collects all of these for you. This page explains each one so you can trust, trim, or rebuild that collection.

## Info.plist

To collect the IDFA, add a tracking usage description. Nothing else here needs a permission.

```xml theme={null}
<key>NSUserTrackingUsageDescription</key>
<string>We use your data to attribute installs and measure ad performance.</string>
```

## What to send

| Field                                                          | Source on iOS                            | Importance                               |
| -------------------------------------------------------------- | ---------------------------------------- | ---------------------------------------- |
| `adservices_attribution_token`                                 | `AAAttribution.attributionToken()`       | **High**. Apple Search Ads attribution.  |
| `idfa`                                                         | `ASIdentifierManager`, after ATT consent | **High**, when the user allows tracking. |
| `idfv`                                                         | `UIDevice.identifierForVendor`           | Recommended. Matching fallback.          |
| `device`, `device_name`, `system_version`                      | `UIDevice`                               | Recommended.                             |
| `brand`, `manufacturer`                                        | Always `"Apple"`                         | Recommended.                             |
| `version`, `build_number`, `bundle_id`                         | `Bundle.main`                            | Recommended.                             |
| `locale`, `language`, `country`, `timezone`, `timezone_offset` | `Locale`, `TimeZone`                     | Recommended.                             |
| `device_display`                                               | `UIScreen.main`                          | Optional.                                |
| `user_agent`, `connectivity`                                   | App-defined, `NWPathMonitor`             | Optional.                                |

<Warning>
  If you send neither `adservices_attribution_token` nor `idfa`, install registration still works, but paid attribution for Apple Search Ads and ad-network matching will be weak or missing.
</Warning>

## Apple Search Ads attribution token

This is the most reliable iOS attribution signal and needs no user permission. The `AdServices` framework returns a short-lived token that Linkrunner exchanges with Apple server-side.

```swift theme={null}
import AdServices

func adServicesToken() -> String? {
    try? AAAttribution.attributionToken()
}
```

<Tip>
  The token is valid only briefly. Fetch it fresh each time you build `device_data` rather than caching it.
</Tip>

## Advertising ID (IDFA)

The IDFA is only available after the user grants App Tracking Transparency. Add `NSUserTrackingUsageDescription`, prompt while the app is active, then read the IDFA.

```swift theme={null}
import AppTrackingTransparency
import AdSupport

// Prompt once, when the app is active (for example after the first screen appears)
func requestTracking() async {
    await withCheckedContinuation { cont in
        ATTrackingManager.requestTrackingAuthorization { _ in cont.resume() }
    }
}

// Read the IDFA only if the user authorized tracking
func idfa() -> String? {
    guard ATTrackingManager.trackingAuthorizationStatus == .authorized else { return nil }
    return ASIdentifierManager.shared().advertisingIdentifier.uuidString
}
```

If your app targets children, do not request tracking and do not collect the IDFA.

## Vendor ID (IDFV)

The IDFV needs no permission. It is stable across your apps on the same device, but resets when the user removes all of your apps.

```swift theme={null}
import UIKit

let idfv = await UIDevice.current.identifierForVendor?.uuidString
```

## SKAdNetwork

iOS measures ad-driven installs through SKAdNetwork. After you call `init`, `signup`, `capture-event`, or `capture-payment`, the response can include a conversion value:

```json theme={null}
{
  "data": {
    "fine_conversion_value": 12,
    "coarse_conversion_value": "medium",
    "lock_postback": false
  }
}
```

Apply it with `SKAdNetwork.updatePostbackConversionValue`. The [full client](/sdk-less/ios-quickstart#skadnetwork) does this for you in `applySKAN`. See [SKAdNetwork integration](/features/skadnetwork-integration) for the dashboard side.

## Everything else

Plain framework lookups. The [full client](/sdk-less/ios-quickstart) includes them.

* `device`, `device_name`, `system_version`: `UIDevice.current`
* `device_display`: `UIScreen.main.bounds` and `scale`
* `locale`, `language`, `country`: `Locale.current`
* `timezone`, `timezone_offset`: `TimeZone.current`
* App info: `Bundle.main` for `version` (`CFBundleShortVersionString`), `build_number` (`CFBundleVersion`), and `bundle_id`

**Need help?** Contact [support@linkrunner.io](mailto:support@linkrunner.io)