Connect to a reader

To start, make sure your reader is powered on and within close proximity.

Then from your app, search for nearby Bluetooth-connected readers with the discoverReaders method, using BluetoothScanDiscoveryConfiguration.

import StripeTerminal

class DiscoverReadersViewController: UIViewController, DiscoveryDelegate {

    var discoverCancelable: Cancelable?

    // ...

    // Action for a "Discover Readers" button
    func discoverReadersAction() throws {
        let config = try BluetoothScanDiscoveryConfigurationBuilder().build()
        self.discoverCancelable = Terminal.shared.discoverReaders(config, delegate: self) { error in
            if let error = error {
                print("discoverReaders failed: \(error)")
            } else {
                print("discoverReaders succeeded")
            }
        }
    }

    // ...

    // MARK: DiscoveryDelegate

    func terminal(_ terminal: Terminal, didUpdateDiscoveredReaders readers: [Reader]) {
        // In your app, display the discovered readers to the user.
        // Call `connectReader` after the user selects a reader to connect to.
    }
}

Bluetooth proximity * BBPOS Chipper 2X BT only

Bluetooth proximity filters search results to return the closest reader. When discovered, the reader flashes multicolored lights, allowing your user to identify the discovered reader among many other readers. After the SDK discovers a reader, it won’t switch to a closer reader unless you turn off the discovered reader.

Note that when using Bluetooth proximity, the SDK returns the reader to your app’s callback twice. The first time, your app receives a Reader object populated with only the reader’s serial number. After a short delay, your app receives the same Reader object populated with new information, such as the reader’s battery level.

We recommend displaying the discovered reader in your app’s UI, letting the user either confirm connection to the reader or cancel if they don’t want to connect to this reader.

Bluetooth scan

Bluetooth scan searches for all nearby readers and returns a list of discovered readers to your app. As the discovery process continues, the SDK continues to invoke the DiscoveryDelegate.didUpdateDiscoveredReaders method with the latest list of nearby readers.

During the discovery process, the Terminal’s SCPConnectionStatus transitions to SCPConnectionStatus.SCPConnectionStatusDiscovering while the discovery is in progress.

With the Bluetooth scan discovery method, you can set a timeout to scan for a set period of time, which you can use for managing battery life or triggering an error message if no devices are found.

In your mobile application, we recommend displaying an auto-updating list of discovered readers, with serial numbers or labels to help users identify their reader.

To connect to a discovered reader, call the connectReader method from your app.

You must register your reader to a location upon connection. To do so, create and use a BluetoothConnectionConfiguration with the locationId set to the relevant location ID when connecting.

// Call `connectReader` with the selected reader and a connection config
// to register to a location as set by your app.
let connectionConfig: BluetoothConnectionConfiguration
do {
    connectionConfig = try BluetoothConnectionConfigurationBuilder(delegate: yourMobileReaderDelegate, locationId: 
"{{LOCATION_ID}}")
    .build()
} catch {
    // Handle the error building the connection configuration
    return
}
Terminal.shared.connectReader(selectedReader, connectionConfig: connectionConfig) { reader, error in
    if let reader = reader {
        print("Successfully connected to reader: \(reader)")
    } else if let error = error {
        print("connectReader failed: \(error)")
    }
}

For your app to run in the background and remain connected to the reader, configure your app to include the required background mode.

Handle reader disconnects

Reader disconnects can sometimes occur between your app and the reader. For example, the reader can disconnect from your app if it’s out of range or runs out of battery. You can simulate an unexpected disconnect while testing by powering off the reader.

The MobileReaderDelegate includes a reader:didDisconnect: method that provides your application with the DisconnectReason to help identify why the reader disconnected.

When a reader disconnects, we automatically attempt reconnection by default and recommend that you display notifications in your app relaying the reader status throughout the process.

To display notifications in your app during automatic reconnection, do the following:

1. Implement the reader reconnect callbacks in the MobileReaderDelegate.
2. Pass the MobileReaderDelegate to your BluetoothConnectionConfiguration.
   ReaderViewController.swift

   Swift

   let connectionConfig: BluetoothConnectionConfiguration
   do {
       connectionConfig = BluetoothConnectionConfigurationBuilder(delegate: yourMobileReaderDelegate, locationId: presentLocationId)
           .build()
   } catch {
       // Handle error building the connection configuration
       return
   }
   
   Terminal.shared.connectReader(reader, connectionConfig: connectionConfig, completion: connectCompletion)

3. When the SDK sends reader:didStartReconnect:disconnectReason: to your app, display a message announcing that the reader lost connection and reconnection is in progress.
   • You can use the Cancelable object to stop the reconnection attempt at any time.
4. When the SDK indicates successful reconnection by sending readerDidSucceedReconnect:, display a message announcing the connection was restored and to continue normal operations.
5. If the SDK can’t reconnect to the reader and sends both readerDidFailReconnect: and reader:didDisconnect:, display a message stating that an unexpected disconnect occurred.

import StripeTerminal

extension ReaderViewController: MobileReaderDelegate {
    // MARK: MobileReaderDelegate

    func reader(_ reader: Reader, didStartReconnect cancelable: Cancelable, disconnectReason: DisconnectReason) {
        // 1. Notified at the start of a reconnection attempt
        // Use cancelable to stop reconnection at any time
    }

    func readerDidSucceedReconnect(_ reader: Reader) {
        // 2. Notified when reader reconnection succeeds
        // App is now connected
    }
    func readerDidFailReconnect(_ reader: Reader) {
        // 3. Notified when reader reconnection fails
        // App is now disconnected
    }
}

To handle reader disconnects yourself, you can do the following:

1. Set autoReconnectOnUnexpectedDisconnect to false during connection.
2. Handle the disconnect callback to display a message in the app alerting the user that the reader unexpectedly disconnected and initiate reader discovery and connection.

import StripeTerminal

class ReaderViewController: UIViewController, MobileReaderDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        // Set the reader delegate when connecting to a reader
    }

    // ...



    func reader(_ reader: Reader, didDisconnect reason: DisconnectReason) {
        // Consider displaying a UI to notify the user and start rediscovering readers
    }
}

Reboot the connected reader

Stripe Reader M2 and BBPOS WisePad 3 automatically reboot after operating for 24 hours. However, you can force the reader to reboot and reset its 24-hour timer by using the rebootReader API. After this action, the reader disconnects from the SDK and then reboots. If you’re using automatic reconnect, the SDK attempts to restore the connection with the reader.

Terminal.shared.rebootReader { error in
    if let error = error {
        // Placeholder for handling the error
    } else {
        // Reboot succeeded and the reader will disconnect.
        // If your app is using automatic reconnect the reconnect will begin.
    }
}

Automatic reconnection on application start

Stripe Terminal doesn’t automatically reconnect to a reader when your application starts. Instead, you can build a reconnection flow by storing reader IDs and attempting to connect to a known reader on startup.

1. When you successfully connect to a reader, save its serial number in a persistent data storage location, such as the UserDefaults API (iOS).

1. When your app launches, check the persistent data storage location for a saved serial number. If one is found, call the discoverReaders method so your application can try to find that reader again.
2. If the saved serial number matches any of the discovered readers, try connecting to that reader with the matching reader object returned from the call to discoverReaders. If the previously connected reader isn’t found, stop the discovery process.

Display some UI during the discovery and connection process to indicate that an automatic reconnection is happening.

Your application must update mobile readers to apply the following:

• Regional configurations that keep you up to date with card network and issuer requirements
• Security updates

Required updates start installing on connection to the reader. You can’t use the reader until updating completes.

Required updates

When immediately required updates are available for the reader, the integration’s MobileReaderDelegate receives the didStartInstallingUpdate callback with a ReaderSoftwareUpdate.

The ReaderSoftwareUpdate provides the necessary details of the update, including an estimate of the total update duration, indicated by durationEstimate.

During the installation process, the Terminal’s connectionStatus transitions to connecting while the update installs on the reader.

Your application must notify users that an update is installing and display the progress in your UI. Make it clear why connecting might take longer than usual.

If the required update process fails, Stripe communicates the error to the MobileReaderDelegate with didFinishInstallingUpdate. You can’t reconnect to the reader after a required update fails, unless the following conditions are met:

• The reader runs the latest software version for the location within the last 30 days.
• The iOS SDK version is greater than or equal to 3.5.0.

If the conditions are met, the connection process succeeds despite an incomplete update. Stripe retries the required update the next time you connect to that reader until it’s successfully installed.

import UIKit
import StripeTerminal

class ReaderViewController: UIViewController, MobileReaderDelegate {

    // ...

    // MARK: MobileReaderDelegate

    func reader(_ reader: Reader, didStartInstallingUpdate update: ReaderSoftwareUpdate, cancelable: Cancelable?) {
        // Show UI communicating that a required update has started installing
    }

    func reader(_ reader: Reader, didReportReaderSoftwareUpdateProgress progress: Float) {
        // Update the progress of the installation
    }

    func reader(_ reader: Reader, didFinishInstallingUpdate update: ReaderSoftwareUpdate?, error: Error?) {
        // Report success or failure of the update
    }

    // ...
}

You can cancel required updates using the Cancelable object, which also results in a failed connection to the reader. You can’t cancel incremental-only updates.

Optional updates

You can defer optional updates until the specified date, after which they become required. The SDK notifies you of optional updates through the MobileReaderDelegate any time the reader is connected but not performing a transaction. If an optional update is available, your application’s MobileReaderDelegate receives the didReportAvailableUpdate callback with the ReaderSoftwareUpdate object containing the update details, including:

• Estimated time for update to complete (durationEstimate)
• Timestamp after which the update becomes required (requiredAt)

In your application, notify users that an update is available, and display a prompt to optionally continue with the update.

To proceed with the update previously reported with didReportAvailableUpdate, call Terminal.shared.installAvailableUpdate.

The available update is also stored on the reader object as reader.availableUpdate.

As the update proceeds, block the user from leaving the page in your app, and instruct the user to keep the reader in range and powered on until the update completes. We recommend also providing your user with a visual indicator of the update’s progress. The MobileReaderDelegate reports the update’s progress in the didReportReaderSoftwareUpdateProgress method.

When an optional update’s requiredAt date has passed, the update installs the next time the reader is connected.

import UIKit
import StripeTerminal

class ReaderViewController: UIViewController, MobileReaderDelegate {

    // ...

    // MARK: MobileReaderDelegate

    func reader(_ reader: Reader, didReportAvailableUpdate update: ReaderSoftwareUpdate) {
        // An update is available for the connected reader. Show this update in your application.
        // Install this update using `Terminal.shared.installAvailableUpdate`.
    }

}

See Testing reader updates to learn more about making sure your application handles the different update types that a reader can have.