For our new friends:

Logto is an Auth0 alternative designed for modern apps and SaaS products. It offers both Cloud and Open-source services to help you quickly launch your identity and management (IAM) system. Enjoy authentication, authorization, and multi-tenant management all in one.

We recommend starting with a free development tenant on Logto Cloud. This allows you to explore all the features easily.

In this article, we will go through the steps to quickly build the Slack sign-in experience (user authentication) with iOS (Swift) and Logto.

Prerequisites

• A running Logto instance. Check out the introduction page to get started.
• Basic knowledge of iOS (Swift).
• A usable Slack account.

Create an application in Logto

Logto is based on OpenID Connect (OIDC) authentication and OAuth 2.0 authorization. It supports federated identity management across multiple applications, commonly called Single Sign-On (SSO).

To create your Native app application, simply follow these steps:

1. Open the Logto Console. In the "Get started" section, click the "View all" link to open the application frameworks list. Alternatively, you can navigate to Logto Console > Applications, and click the "Create application" button.
2. In the opening modal, click the "Native app" section or filter all the available "Native app" frameworks using the quick filter checkboxes on the left. Click the "iOS (Swift)" framework card to start creating your application.
3. Enter the application name, e.g., "Bookstore," and click "Create application".

🎉 Ta-da! You just created your first application in Logto. You'll see a congrats page which includes a detailed integration guide. Follow the guide to see what the experience will be in your application.

Integrate iOS (Swift) with Logto

Add Logto SDK as a dependency

note:

The minimum supported iOS version of Logto Swift SDK is iOS 13.

Logto Swift SDK comes in two major versions:

• v1: Opens the sign-in experience in an embedded WebView, which is required by the native social plugin targets, but does not support passkey sign-in (WebView does not support WebAuthn, the underlying standard of passkeys).
• v2 (beta): Opens the sign-in experience in ASWebAuthenticationSession (the system browser), which unlocks passkey sign-in and shares the browser session. Note that v2 removes the native social plugin targets; social connectors still work through the browser. If you depend on the native WeChat or Alipay SDK handoff, stay on v1.

This guide covers both versions. Choose your version in the tabs below, and the choice will be kept in sync throughout this guide.

Use the following URL to add Logto SDK as a dependency in Swift Package Manager.

https://github.com/logto-io/swift.git

Since Xcode 11, you can directly import a Swift package w/o any additional tool.

When Xcode asks for the package version, choose the version you want to integrate:

v2 (beta)

v2 is released as 2.0.0-beta.x prereleases until GA. Use 2.0.0-beta.1 or the latest 2.0.0-beta.x prerelease as the version. During beta, we recommend selecting the prerelease explicitly instead of relying on a normal version range to pick it automatically.

If you use Package.swift directly:

Package.swift

.package(url: "https://github.com/logto-io/swift.git", exact: "2.0.0-beta.1")

v1

Use the latest v1 release as the stable line. The latest v1 version is 1.2.0.

If you use Package.swift directly:

Package.swift

.package(url: "https://github.com/logto-io/swift.git", from: "1.2.0")

We do not support Carthage and CocoaPods at the time due to some technical issues.

Carthage

Carthage needs a xcodeproj file to build. We will try to find a workaround later.

CocoaPods

CocoaPods does not support local dependency and monorepo, thus it's hard to create a .podspec for this repo.

Init LogtoClient

Initialize the client by creating a LogtoClient instance with a LogtoConfig object.

ContentView.swift

import Logto
import LogtoClient

let config = try? LogtoConfig(
  endpoint: "<your-logto-endpoint>", // E.g. http://localhost:3001
  appId: "<your-app-id>"
)
let client = LogtoClient(useConfig: config)

info:

By default, we store credentials like ID Token and Refresh Token in the Keychain. Thus the user doesn't need to sign in again when he returns.

To turn off this behavior, set usingPersistStorage to false:

let config = try? LogtoConfig(
  // ...
  usingPersistStorage: false
)

Sign in

Before we dive into the details, here's a quick overview of the end-user experience. The sign-in process can be simplified as follows:

1. Your app invokes the sign-in method.
2. The user is redirected to the Logto sign-in page. For native apps, the system browser is opened.
3. The user signs in and is redirected back to your app (configured as the redirect URI).

Regarding redirect-based sign-in

1. This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
2. If you have multiple apps, you can use the same identity provider (Logto). Once the user signs in to one app, Logto will automatically complete the sign-in process when the user accesses another app.

To learn more about the rationale and benefits of redirect-based sign-in, see Logto sign-in experience explained.

Configure redirect URI

v2 (beta)

Let's switch to the Application details page of Logto Console. Add a Redirect URI io.logto.app://callback and click "Save changes".

In v2, the sign-in experience opens in ASWebAuthenticationSession (the system browser), and the redirect is routed back to your app through OS-level callback matching. For a custom scheme redirect URI such as io.logto.app://callback, register only the scheme part (io.logto.app) in your app's Info.plist, then add the full redirect URI to your Logto application's Redirect URIs.

In Xcode, open your app target, select Info, expand URL Types, and add one entry with io.logto.app in URL Schemes. If you edit Info.plist directly, add:

Info.plist

<key>CFBundleURLTypes</key>
<array>
  <dict>
    <key>CFBundleTypeRole</key>
    <string>Editor</string>
    <key>CFBundleURLName</key>
    <string>io.logto.app</string>
    <key>CFBundleURLSchemes</key>
    <array>
      <string>io.logto.app</string>
    </array>
  </dict>
</array>

For the browser flow in v2, you do not need to call LogtoClient.handle(url:); that plugin handoff API was removed with the embedded WebView flow.

Use Universal Links instead of a custom scheme?

You can also use an HTTPS redirect URI such as https://example.com/callback:

1. Add the Associated Domains capability to your app.
2. Configure webcredentials:example.com so ASWebAuthenticationSession can match HTTPS callbacks on iOS 17.4 and newer.
3. If the same URL should also open your app as a Universal Link outside the authentication session, configure applinks:example.com and host a valid apple-app-site-association file for the domain and path.
4. Add the HTTPS URI to your Logto application's Redirect URIs.
5. Pass the same URI to signInWithBrowser.

On iOS 17.4 and newer, the SDK uses ASWebAuthenticationSession's HTTPS callback matching API so HTTPS redirects can automatically complete and dismiss the session. On older iOS versions, the authorization request can still use the HTTPS redirect URI, but the session may not close automatically unless your app handles the Universal Link callback itself. Keep a custom scheme redirect as a compatibility option if you need automatic completion on older iOS versions.

v1

Let's switch to the Application details page of Logto Console. Add a Redirect URI io.logto://callback and click "Save changes".

info:

The Redirect URI in iOS SDK is only for internal use. There's NO NEED to add a Custom URL Scheme until a connector asks.

Sign-in and sign-out

note:

Before calling .signInWithBrowser(redirectUri:), make sure you have correctly configured Redirect URI in Admin Console.

v2 (beta)

In v2, client.signOut(postLogoutRedirectUri:) performs a complete sign-out: it clears the local credentials, revokes the refresh token, and ends the Logto session by opening the end session endpoint in the system browser. The browser then navigates back to your app through the post sign-out redirect URI. Before using it, switch to the application details page of Logto Console, add the post sign-out redirect URI io.logto.app://signed-out and click "Save changes". The post sign-out redirect URI can use the same custom scheme you registered for sign-in.

For example, in a SwiftUI app:

ContentView.swift

struct ContentView: View {
  @State var isAuthenticated: Bool

  private let redirectUri = "io.logto.app://callback"
  private let postLogoutRedirectUri = "io.logto.app://signed-out"

  init() {
    isAuthenticated = client.isAuthenticated
  }

  var body: some View {
    VStack {
      if isAuthenticated {
        Button("Sign Out") {
          Task { [self] in
            let error = await client.signOut(postLogoutRedirectUri: postLogoutRedirectUri)
            if let error = error {
              print(error)
              return
            }
            isAuthenticated = false
          }
        }
      } else {
        Button("Sign In") {
          Task { [self] in
            do {
              try await client.signInWithBrowser(redirectUri: redirectUri)
              isAuthenticated = true
            } catch let error as LogtoClientErrors.SignIn {
              // error occurred during sign in
            } catch {
              // other errors
            }
          }
        }
      }
    }
  }
}

note:

• You can also call client.signOut() without a post sign-out redirect URI. No Console configuration is needed in this case: the browser shows the Logto sign-out page, and the user returns to the app by dismissing it manually.
• If no UI context is available, you can call client.clearCredentials() to clear the local credentials and revoke the refresh token. Note that this keeps the Logto session in the browser, so the next signInWithBrowser may silently sign the user back in through that session.

v1

You can use client.signInWithBrowser(redirectUri:) to sign in the user and client.signOut() to sign out the user.

For example, in a SwiftUI app:

ContentView.swift

struct ContentView: View {
  @State var isAuthenticated: Bool

  init() {
    isAuthenticated = client.isAuthenticated
  }

  var body: some View {
    VStack {
      if isAuthenticated {
        Button("Sign Out") {
          Task { [self] in
            await client.signOut()
            isAuthenticated = false
          }
        }
      } else {
        Button("Sign In") {
          Task { [self] in
            do {
              try await client.signInWithBrowser(redirectUri: "io.logto://callback")
              isAuthenticated = true
            } catch let error as LogtoClientErrors.SignIn {
              // error occurred during sign in
            } catch {
              // other errors
            }
          }
        }
      }
    }
  }
}

Checkpoint: Test your application

Now, you can test your application:

1. Run your application, you will see the sign-in button.
2. Click the sign-in button, the SDK will init the sign-in process and redirect you to the Logto sign-in page.
3. After you signed in, you will be redirected back to your application and see the sign-out button.
4. Click the sign-out button to clear token storage and sign out.

Add Slack connector

To enable quick sign-in and improve user conversion, connect with iOS (Swift) as an identity provider. The Logto social connector helps you establish this connection in minutes by allowing several parameter inputs.

To add a social connector, simply follow these steps:

1. Navigate to Console > Connectors > Social Connectors.
2. Click "Add social connector" and select "Slack".
3. Follow the README guide and complete required fields and customize settings.

note:

If you are following the in-place Connector guide, you can skip the next section.

Set up Slack OAuth app

Set up Slack App

Go to the Slack API: Applications and sign in with your Slack account. If you don’t have an account, you can register for one.

Then, create an app.

Step 1: Find Client ID and Client Secret.

You can find the Client ID and Client Secret on the "Basic Information" section.

Step 2: Set up redirect URLs.

Go to the "OAuth & Permissions" section, you can find the "Redirect URLs" form.

In our case, this will be ${your_logto_endpoint}/callback/${connector_id}. e.g. https://foo.logto.app/callback/${connector_id}. The connector_id can be found on the top bar of the Logto Admin Console connector details page.

You can refer to the Slack API documentation for more details.

Configure your connector

In your Logto connector configuration, fill out the following fields with the values obtained from your App's "Keys and tokens" page's "OAuth 2.0 Client ID and Client Secret" section:

• clientId: Your App's Client ID.
• clientSecret: Your App's Client Secret.

scope is a space-delimited list of OpenID scopes. If not provided, the default scope is openid profile.

Config types

Name	Type
clientId	string
clientSecret	string
scope	string

Save your configuration

Double check you have filled out necessary values in the Logto connector configuration area. Click "Save and Done" (or "Save changes") and the Slack connector should be available now.

Enable Slack connector in Sign-in Experience

Once you create a social connector successfully, you can enable it as a "Continue with Slack" button in Sign-in Experience.

1. Navigate to Console > Sign-in & account > Sign-up and sign-in.
2. (Optional) Choose "Not applicable" for sign-up identifier if you need social login only.
3. Add configured Slack connector to the "Social sign-in" section.

Testing and Validation

Return to your iOS (Swift) app. You should now be able to sign in with Slack. Enjoy!

Further readings

End-user flows: Logto provides a out-of-the-box authentication flows including MFA and enterprise SSO, along with powerful APIs for flexible implementation of account settings, security verification, and multi-tenant experience.

Authorization: Authorization defines the actions a user can do or resources they can access after being authenticated. Explore how to protect your API for native and single-page applications and implement Role-based Access Control (RBAC).

Organizations: Particularly effective in multi-tenant SaaS and B2B apps, the organization feature enable tenant creation, member management, organization-level RBAC, and just-in-time-provisioning.

Customer IAM series Our serial blog posts about Customer (or Consumer) Identity and Access Management, from 101 to advanced topics and beyond.