Approov Quickstart: iOS and watchOS Swift URLSession

This quickstart is written specifically for native iOS and watchOS apps that are written in Swift and making API calls using URLSession that you wish to protect with Approov. If this is not your situation then check if there is a more relevant quickstart guide available.

This page provides all the steps for integrating Approov into your app. Additionally, a step-by-step tutorial guide using our Shapes App Example is also available which provides an iOS and watchOS applications.

To follow this guide you should have received an onboarding email for a trial or paid Approov account.

Note that the minimum requirement is iOS 12 and watchOS 7. You cannot use Approov in apps that support iOS versions older than this.

ADDING APPROOV SERVICE DEPENDENCY

The Approov integration is available via the Swift Package Manager. This allows inclusion into the project by simply specifying a dependency in the File -> Add Packages... Xcode option if the project is selected:

Enter the repositoryhttps://github.com/approov/approov-service-urlsession.git into the search box. You will then have to select the relevant version you wish to use. To do so, select the Exact Version option and enter a specific option you require or use the latest available tag, which should be selected for you.

Once you click Add Package the last step will confirm the package product and target selection. The approov-service-urlsession is actually an open source wrapper layer that allows you to easily use Approov with URLSession. This has a further dependency to the closed source Approov SDK.

Alternatively, use cocoapods and add the package dependecies similar to how they are used in the example shapes-app/Podfile in this repository.

USING APPROOV SERVICE

The ApproovURLSession class mimics the interface of the URLSession class provided by Apple but includes an additional Approov attestation calls. The simplest way to use the ApproovURLSession class is to find and replace all the URLSession construction calls with ApproovURLSession.

try! ApproovService.initialize("<enter-your-config-string-here>")
let session = ApproovURLSession(URLSessionConfiguration.default)

Additionally, the Approov SDK wrapper class, ApproovService needs to be initialized before using the ApproovURLSession object. The <enter-your-config-string-here> is a custom string that configures your Approov account access. This will have been provided in your Approov onboarding email (it will be something like #123456#K/XPlLtfcwnWkzv99Wj5VmAxo4CrU267J1KlQyoz8Qo=).

For API domains that are configured to be protected with an Approov token, this adds the Approov-Token header and pins the connection. This may also substitute header values when using secrets protection.

ERROR TYPES

The ApproovService functions may throw specific errors to provide additional information:

• permanentError might be due to a feature not enabled using the command line
• rejectionError an attestation has been rejected, the ARC and rejectionReasons may contain specific device information that would help troubleshooting
• networkingError generaly can be retried since it can be temporary network issue
• pinningError is a certificate error
• configurationError a configuration feature is disabled or wrongly configured (i.e. attempting to initialize with different config from a previous instantiation)
• initializationFailure the ApproovService failed to be initialized (subsequent network requests will not be performed)

CHECKING IT WORKS

Initially you won't have set which API domains to protect, so the interceptor will not add anything. It will have called Approov though and made contact with the Approov cloud service. You will see logging from Approov saying unknown URL.

Your Approov onboarding email should contain a link allowing you to access Live Metrics Graphs. After you've run your app with Approov integration you should be able to see the results in the live metrics within a minute or so. At this stage you could even release your app to get details of your app population and the attributes of the devices they are running upon.

NEXT STEPS

To actually protect your APIs and/or secrets there are some further steps. Approov provides two different options for protection:

• API PROTECTION: You should use this if you control the backend API(s) being protected and are able to modify them to ensure that a valid Approov token is being passed by the app. An Approov Token is short lived crytographically signed JWT proving the authenticity of the call.

• SECRETS PROTECTION: This allows app secrets, including API keys for 3rd party services, to be protected so that they no longer need to be included in the released app code. These secrets are only made available to valid apps at runtime.

Note that it is possible to use both approaches side-by-side in the same app.

See REFERENCE for a complete list of all of the ApproovService methods.

DATA TASK PUBLISHER

The version of dataTaskPublisher(for:) provided in URLSession does not add Approov protection.

If you wish to use an Approov protected version then please call dataTaskPublisherApproov instead. Note though that this method may block when it is called when requesting network communication with the Approov cloud. Therefore you shouldn't call this method from the main UI thread.

AWAIT-ASYNC ASYNCHRONOUS TRANSFERS

Note that the methods related to Performing Asynchronous Transfers (introduced in iOS 15, and discussed in Using URLSession’s async/await-powered APIs) should not be called directly and do not provide Approov protection. This is because they are defined in an extension to URLSession and cannot be overridden by the Approov implementation. Instead various of the methods are provided with an identical method signature but have a WithApproov suffix in their name. The supported methods are as follows:

dataWithApproov(for request: URLRequest, delegate: URLSessionTaskDelegate? = nil) async throws -> (Data, URLResponse)

dataWithApproov(from url: URL, delegate: URLSessionTaskDelegate? = nil) async throws -> (Data, URLResponse)

uploadWithApproov(for request: URLRequest, fromFile fileURL: URL, delegate: URLSessionTaskDelegate? = nil) async throws -> (Data, URLResponse)

uploadWithApproov(for request: URLRequest, from bodyData: Data, delegate: URLSessionTaskDelegate? = nil) async throws -> (Data, URLResponse)

downloadWithApproov(for request: URLRequest, delegate: URLSessionTaskDelegate? = nil) async throws -> (URL, URLResponse)

downloadWithApproov(from url: URL, delegate: URLSessionTaskDelegate? = nil) async throws -> (URL, URLResponse)