Sign In with Email/Phone Number

Our iOS SDK offers the easiest way to verify email/phone numbers in your Swift app. You can simply call a function and it does most of the heavy lifting and authentication for you.

Concepts: Learn about how Sign in with Email/Phone Number works.

Overview

Verifying email and phone number in your mobile app using our iOS SDK consists of the following steps:

1. Import Cotter

2. Call Cotter's Login function

3. Receive user's email or phone number, and whether or not it's verified

What you're building

Cotter's iOS SDK

Steps

1. Import Cotter as dependency
2. Initialize Cotter with your API Key
3. Call Cotter's Login Function
4. Receive Token

Step 1. Import Cotter as dependency

We use Cocoapods as our SDK host. If you're using Cocoapods, add this to your Podfile

pod 'Cotter'

Then simply run pod install

Step 2. Initialize Cotter with your API Key

You will have to do import Cotter on the file that will use Cotter. Then do initialization as follows

import Cotter

...

let cotter = Cotter(
    apiSecretKey: <your-api-secret-key>,
    apiKeyID: <your-api-key-id>,
    cotterURL: "https://www.cotter.app/api/v0",
    userID: <your-user-id>, // user's id that will be created later
    configuration: <your-cotter-config>
)

example:

import Cotter

...

let cotter = Cotter(
    apiSecretKey: "<API_SECRET_KEY>",
    apiKeyID: "<API_KEY_ID>",
    cotterURL: "https://www.cotter.app/api/v0",
    userID: "[e-mail]",
    configuration: [:]
  );

Step 3. Call Cotter's login function

cotter.startPasswordlessLogin(
            parentView: <your-view-controller>,
            input: <your-input-text>,
            identifierField: <identifier>,
            type: <PHONE-or-EMAIL>,
            directLogin: <true-or-false>,
            cb: <your-callback>
        )

example:

@available(iOS 12.0, *)
class LoginViewController: UIViewController {
    @IBOutlet weak var loginButton: UIButton!
    @IBOutlet weak var phoneInput: UITextField!

    ...

    @IBAction func login(_ sender: Any) {
        // get the text input
        let textInput = self.phoneInput.text ?? ""

        func authCb(accessToken: String, error: Error?) -> Void{
            guard let error = error else {
                print("error logging in!")
                return
            }

            // error handling
            print("success!")
        }

        let cotter = Cotter(
          apiSecretKey: "<API_SECRET_KEY>",
          apiKeyID: "<API_KEY_ID>",
          cotterURL: "https://www.cotter.app/api/v0",
          userID: "[e-mail]",
          configuration: [:]
        );

        cotter.startPasswordlessLogin(
            parentView: self,
            input: textInput,
            identifierField: "phone",
            type: "PHONE",
            directLogin: true,
            cb: authCb
        )
    }
}

To login and enter email or phone number in Cotter's window, simply set the directLogin to false and set the input to empty string

cotter.startPasswordlessLogin(
    parentView: self,
    input: "",
    identifierField: "phone",
    type: "PHONE",
    directLogin: false,
    cb: authCb
)

To send code/link via SMS or WhatsApp, you'll need to add some balance to you project in the Dashboard.

Step 4: Receive Token

The token will be received in the callback function. The token will be in the form as the following:

"token": {
  "identifier": "[phone]",
  "identifier_type": "PHONE",
  "receiver": "<your API_KEY_ID>",
  "expire_at": "1584687591",
  "signature": "G8dOKR6qLj+GiB0pD2aggVVdYddFoyy..."
}

The token contains the user's phone number, your API_KEY_ID in the receiver field, and a signature to ensure this is from Cotter. The token tells you that this identifier is verified.

You should include this JSON Object into your call to your backend for Login or Registration. Your backend should then verify that the signature of the token is valid.

Validating Cotter's Access Token

Checkout how to verify the OAuth Tokens from Cotter here:

Verifying JWT Tokens

🎉 You're done!

Securing your Project

Since you'll be using your API Key from a front-end website or mobile app, your API_KEY_ID is exposed to anyone inspecting your code. Here are some ways to prevent abuse:

• Only allow your website/app to use your API Key
• Rate Limit the number of authentication requests
• Enable reCAPTCHA to prevent automated abuse