> ## Documentation Index > Fetch the complete documentation index at: https://docs.nemu.com.br/llms.txt > Use this file to discover all available pages before exploring further. # iOS # iOS-specific considerations iOS has its own rules and limitations related to **privacy**, **attribution**, and **data collection** that directly affect how any tracking SDK works, including the Nemu SDK. This section describes how the SDK behaves on iOS and what limitations are expected from the platform. *** ## Privacy and Apple policies Apple enforces strict restrictions on data collection and sharing, especially after the introduction of **App Tracking Transparency (ATT)**. The Nemu SDK is designed to: * Not rely on identifiers prohibited by Apple * Work correctly even when the user **denies tracking consent** * Comply with the App Store privacy policies The SDK does not use IDFA as a requirement for basic attribution functionality. *** ## App Tracking Transparency (ATT) On devices running iOS 14.5 or later, the system may ask the user for explicit permission to track them across third-party apps and websites. ### SDK behavior * The SDK **does not automatically request** ATT permission * It is up to the app to decide **when** and **whether** to display the consent prompt * The absence of consent **does not prevent**: * Capturing UTMs via deep link * Install attribution * Deferred deep links * Logging events in the app ### Recommendation If your app uses ATT, we recommend displaying the prompt **only after clearly explaining to the user** the reason for the request. *** ## Identifiers on iOS Due to Apple's restrictions, the SDK works with identifiers that are compliant with the platform's policies. ### Identifiers used * Identifiers generated by the app itself (e.g., user UID) * Internal session identifiers * Source data provided by the system or by the entry link ### Identifiers not used * IDFA (when not authorized) * Device fingerprinting * Persistent identifiers prohibited by Apple's policies The use of fingerprinting techniques is not allowed on iOS and is not adopted by the Nemu SDK. *** ## Attribution on iOS ### Install attribution On iOS, install attribution may have limitations depending on: * The source of the click * The permissions granted by the user * The information made available by the system When available, the SDK associates the install source with the app's first session. ### Deferred Deep Links Deferred deep links on iOS work according to the platform's capabilities and may vary depending on: * The type of link used * The iOS version * The app's configuration In some scenarios, iOS may limit or delay the availability of source information after installation. *** ## Deep Links and Universal Links iOS distinguishes between two main types of links: * **Custom URL Schemes** (`myapp://`) * **Universal Links** (`https://` associated with the app) ### Recommendations * Whenever possible, use **Universal Links** * Make sure the app is correctly configured with: * Associated Domains * The `apple-app-site-association` file This improves reliability in capturing UTMs and the user experience. *** ## Data persistence on iOS iOS may terminate background apps aggressively to save resources. For this reason: * Source capture should happen as early as possible * The SDK persists essential information to avoid data loss * Session data can be restored when the app is reopened *** ## Recommended best practices To ensure the best tracking quality on iOS: * Initialize the SDK early in the app's lifecycle * Correctly configure deep links or universal links * Register the user's UID as soon as it is available * Do not rely solely on tracking permissions for basic attribution *** ## Realistic expectations on iOS Due to Apple's policies: * Attribution on iOS may be less deterministic than on Android * Some installation scenarios may not contain an identifiable source * Behavior may vary depending on the system version and permissions These limitations are inherent to the iOS ecosystem and apply to any tracking solution on the market.