update cause

Author: genlin

support/entra/entra-id/app-integration/repeat-login prompts-in-msal-ios-app.md

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+---
+title: Troubleshooting repeated login prompts in iOS MSAL implementation
+description: Provides guidance for troubleshooting repeated login prompts in iOS MSAL implementation
+ms.date: 03/19/2025
+ms.author: bachoang
+ms.service: entra-id
+ms.custom: sap:Microsoft Entra App Integration and Development
+---
+
+# Troubleshooting repeated login prompts in iOS MSAL implementation
+
+This article provides guidance for troubleshooting repeated login prompts in an iOS app that uses Microsoft Authentication Library (MSAL).
+
+## Symptoms
+
+You integrate mobile authentication in your iOS app by using the Microsoft Authentication Library (MSAL) SDK. This is done by following the [official tutorial](/azure/active-directory/develop/tutorial-v2-ios). The user is unexpectedly prompted to log in multiple times after the initial login.
+
+## Cause
+
+This issue is typically caused by MSAL web browser configurations that do not allow cookie sharing.
+
+The tutorial uses the MSAL to implement authentication. MSAL SDK library facilitates authentication by renewing tokens automatically. It also enables single sign-on (SSO) between other apps on the device and manages user accounts.
+
+For SSO to function correctly, tokens must be shared between apps. This requires a token cache or a broker application, such as Microsoft Authenticator for iOS. Interactive authentication in MSAL requires a web browser. On iOS, MSAL uses the system web browser by default for interactive authentication. This default setup supports SSO state sharing between the apps.
+
+However, if you customize the browser configuration for authentication, such as by using one of the following options, cookie sharing might not be enabled by default:
+
+| **For iOS only** | **For iOS and macOS** |
+| --- | --- |
+| [ASWebAuthenticationSession](https://developer.apple.com/documentation/authenticationservices/aswebauthenticationsession?language=objc) <br> [SFAuthenticationSession](https://developer.apple.com/documentation/safariservices/sfauthenticationsession?language=objc) <br> [SFSafariViewController](https://developer.apple.com/documentation/safariservices/sfsafariviewcontroller?language=objc) | [WKWebView](https://developer.apple.com/documentation/webkit/wkwebview?language=objc) |
+
+To customize the browser, you must allow cookie sharing to prevent repeated login prompts.
+
+## Resolution
+
+To enable cookie sharing and prevent repeated login prompts, use one of the following configurations:
+
+- **ASWebAuthenticationSession in MSAL** + **openURL in Safari browser** (the full Safari browser, not SafariViewController).
+- **SFSafariViewController in MSAL** + **SFSafariViewController in your app**.
+- **WKWebView in MSAL** + **WKWebView in your app**.
+
+For more information, see [Customizing webviews and browsers](/azure/active-directory/develop/customize-webviews).
+
+> [!Note]
+> For Xamarin.iOS, several additional factors need to be considered, including enabling token caching and using Microsoft Authenticator. For more information, see [Xamarin.iOS MSAL considerations](/azure/active-directory/develop/msal-net-xamarin-ios-considerations).
+
+[!INCLUDE [Azure Help Support](../../../includes/azure-help-support.md)]
+
+