How to build SendGrid Email passwordless sign-in with iOS (Swift)

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 SendGrid 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 SendGrid 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:

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.
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.
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 Logto SDK

Add Logto SDK as a dependency

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.

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

Carthage

Carthage needs a xcodeproj file to build, but swift package generate-xcodeproj will report a failure since we are using binary targets for native social plugins. 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
)

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:

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

This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
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

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.

note:

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

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: "${
                props.redirectUris[0] ?? 'io.logto://callback'
              }")
              isAuthenticated = true
            } catch let error as LogtoClientErrors.SignIn {
              // error occured during sign in
            } catch {
              // other errors
            }
          }
        }
      }
    }
  }
}

Checkpoint: Test your application

Now, you can test your application:

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

Add SendGrid connector

Email connector is a method used to send one-time passwords (OTPs) for authentication. It enables Email address verification to support passwordless authentication, including Email-based registration, sign-in, two-factor authentication (2FA), and account recovery. You can easily connect SendGrid as your Email provider. With the Logto Email connector, you can set this up in just a few minutes.

To add a Email connector, simply follow these steps:

Navigate to Console > Connector > Email and SMS connectors.
To add a new Email connector, click the "Set up" button and select "SendGrid".
Review the README documentation for your selected provider.
Complete the configuration fields in the "Parameter Configuration" section.
Customize the Email template using the JSON editor.
Test your configuration by sending a verification code to your Email address.

Connector tab

note:

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

Set up SendGrid email connector

Register SendGrid account

Create a new account at SendGrid website. You may skip this step if you've already got an account.

Verify senders

Go to the SendGrid console page and sign in with your SendGrid account.

Senders indicate the addresses our verification code email will be sent from. In order to send emails via the SendGrid mail server, you need to verify at least one sender.

Starting from the SendGrid console page, go to "Settings" -> "Sender Authentication" from the sidebar.

Domain Authentication is recommended but not obligatory. You can click "Get started" in "Authenticate Your Domain" card and follow the upcoming guide to link and verify a sender to SendGrid.

By clicking the "Verify a Single Sender" button in the panel, you are now focusing on a form requiring some critical information to create a sender. Follow the guide, fill out all these fields, and hit the "Create" button.

After the single sender is created, an email with a verification link should be sent to your sender's email address. Go to your mailbox, find the verification mail and finish verifying the single sender by clicking the link given in the email. You can now send emails via SendGrid connector using the sender you've just verified.

Create API keys

Let's start from the SendGrid console page, go to "Settings" -> "API Keys" from the sidebar.

Click the "Create API Key" in the top-right corner of the API Keys page. Type in the name of the API key and customize "API Key Permission" per your use case. A global Full Access or Restricted Access with full access to Mail Send is required before sending emails with this API key.

The API Key is presented to you on the screen as soon as you finished the Create API Key process. You should save this API Key somewhere safe because this is the only chance that you can see it.

Configure your connector

Fill out the apiKey field with the API Key created in "Create API keys" section.

Fill out the fromEmail and fromName fields with the senders' From Address and Nickname. You can find the sender's details on the "Sender Management" page. fromName is OPTIONAL, so you can skip filling it.

You can add multiple SendGrid mail connector templates for different cases. Here is an example of adding a single template:

Fill out the subject field, which works as the title of emails.
Fill out the content field with arbitrary string-typed contents. Do not forget to leave the {{code}} placeholder for the random verification code.
Fill out usageType field with either Register, SignIn, ForgotPassword, Generic for different use cases.
Fill out type field with either text/plain or text/html for different types of content.

In order to enable full user flows, templates with usageType Register, SignIn, ForgotPassword and Generic are required.

Here is an example of SendGrid connector template JSON.

[
  {
    "subject": "<register-template-subject>",
    "content": "<Logto: Your verification code is {{code}}. (register template)>",
    "usageType": "Register",
    "type": "text/plain",
  },
  {
    "subject": "<sign-in-template-subject>",
    "content": "<Logto: Your verification code is {{code}}. (sign-in template)>",
    "usageType": "SignIn",
    "type": "text/plain",
  },
  {
    "subject": "<forgot-password-template-subject>",
    "content": "<Logto: Your verification code is {{code}}. (forgot-password template)>",
    "usageType": "ForgotPassword",
    "type": "text/plain",
  },
  {
    "subject": "<generic-template-subject>",
    "content": "<Logto: Your verification code is {{code}}. (generic template)>",
    "usageType": "Generic",
    "type": "text/plain",
  },
]

Test SendGrid email connector

You can type in an email address and click on "Send" to see whether the settings can work before "Save and Done".

That's it. Don't forget to Enable connector in sign-in experience

Config types

Name	Type
apiKey	string
fromEmail	string
fromName	string (OPTIONAL)
templates	Template[]

Template Properties	Type	Enum values
subject	string	N/A
content	string	N/A
usageType	enum string	'Register' \| 'SignIn' \| 'ForgotPassword' \| 'Generic'
type	enum string	'text/plain' \| 'text/html'

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 SendGrid connector should be available now.

Once you create a connector successfully, you can enable phone number-based passwordless login and registration.

Navigate to Console > Sign-in experience > Sign-up and sign-in.
Set up sign-up methods (Optional):
1. Select "Email address" or "Email or phone number" as the sign-up identifier.
2. "Verify at sign-up" is forced to be enabled. You can also enable "Create a password" on registration.
Set up sign-in methods:
1. Select Email address as one of sign-in identifiers. You can provide multiple available identifiers (email, phone number, and username).
2. Select "Verification code" and / or "Password" as the authentication factor.
Click "Save changes" and test it in "Live preview".

Sign-in Experience tab

In addition to registration and login via OTPs, you can also have password recovery and -based security verification enabled, as well as linking Email address to profile. See End-user flows for more details.

Testing and Validation

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

Create an application in Logto​

Integrate Logto SDK​

Add Logto SDK as a dependency​

Carthage​

CocoaPods​

Init LogtoClient​

Sign in​

Regarding redirect-based sign-in​

Configure redirect URI​

Sign-in and sign-out​

Checkpoint: Test your application​

Add SendGrid connector​

Set up SendGrid email connector​

Register SendGrid account​

Verify senders​

Create API keys​

Configure your connector​

Test SendGrid email connector​

Config types​

Save your configuration​

Enable SendGrid connector in Sign-in Experience​

Testing and Validation​

Further readings​