Share Activation Data

This chapter explains how to share the PowerAuthSDK activation state between application and its extensions, or between multiple applications from the same vendor.

Prepare Activation Data Sharing

The App Extension normally doesn’t have access to data created by the main application, so the first step is to set up data sharing for your project.

Keychain Sharing

iOS SDK stores its most sensitive data into the iOS keychain, so you need to configure the keychain sharing first. If you’re not familiar with keychain sharing, then don’t worry about that, the keychain is shared only between the vendor’s applications. So the sensitive information is not exposed to 3rd party applications.

1. Select your application project in the Project Navigator to navigate to the target configuration window and select the applications’s target under the TARGETS heading in the sidebar.
2. Now select Signing & Capabilities tab and click + Capability button.
3. Find and add Keychain Sharing capability.
4. Click “+” in just created Keychain Sharing capability and Xcode will predefine first Keychain Group to your application’s bundle name. Let’s call this value as KEYCHAIN_GROUP_NAME

Now you have to do a similar setup for your application’s extension:

1. Select your application project in the Project Navigator to navigate to the target configuration window and select the extensions’s target under the TARGETS heading in the sidebar.
2. Select Signing & Capabilities tab and click + Capability button.
3. Find and add Keychain Sharing capability.
4. Click “+” in just created Keychain Sharing capability and add the same KEYCHAIN_GROUP_NAME as you did for the application’s target.
5. (optional) Repeat steps 4 to 6 for all other extensions which supposed to use shared activation data.

Now you need to know your Team ID (the unique identifier assigned to your team by Apple). Unfortunately, the identifier is not simply visible in Xcode, so you’ll have to log in to Apple’s development portal and look for that identifier on your membership details page.

If you know the Team ID, then the final KEYCHAIN_GROUP_IDENTIFIER constant is composed as TEAM_ID.KEYCHAIN_GROUP_NAME. So, it should look like: KTT00000MR.com.powerauth.demo.App.

App Groups

The PowerAuth SDK for iOS is using one boolean flag stored in the UserDefaults facility, to determine whether the application has been reinstalled. Unfortunately, the UserDefaults.standard created by the application cannot be shared with the app extension, so you have to create a new application group to share that data.

1. Select your application project in the Project Navigator to navigate to the target configuration window and select the applications’s target under the TARGETS heading in the sidebar.
2. Now select Signing & Capabilities tab and click + Capability button.
3. Find and add App Groups capability.
4. Click “+” in just created App Groups capability add a group with the desired identifier and turn this particular group ON (e.g. make sure that the checkmark close to the group’s name is selected). Let’s call this value APP_GROUP_IDENTIFIER. If the group already exists, then just click the checkmark to turn it ON.
5. Now switch to the application’s extension target, select the Capabilities tab, and also expand the App Groups section.
6. Turn “ON” App Groups for extension and add an app group with the same name as you did in step 3.

You can optionally check a troubleshooting section if you need to migrate the keychain initialization flag from standard user defaults to a shared one.

Configure Activation Data Sharing

To share the activation’s state just assign an instance of the PowerAuthSharingConfiguration object into PowerAuthConfiguration:

// Keychain sharing and App Group constants
let keychainSharing = "KTT00000MR.com.powerauth.demo.App"   // KEYCHAIN_GROUP_IDENTIFIER constant
let appGroup = "group.your.app.group"                       // APP_GROUP_IDENTIFIER constant
// Prepare the configuration
let configuration = PowerAuthConfiguration(
        instanceId: Bundle.main.bundleIdentifier!,
        baseEndpointUrl: "https://<your-domain>/enrollment-server",
        configuration: "ARDDj6EB6iAUtNm...KKEcBxbnH9bMk8Ju3K1wmjbA==")
// Assign sharing configuration
configuration.sharingConfiguration = PowerAuthSharingConfiguration(
    appGroup: appGroup,
    appIdentifier: "com.powerauth.demo.App", 
    keychainAccessGroup: keychainSharing)

// Create a PowerAuthSDK instance
let powerAuthSDK = try PowerAuthSDK(configuration: configuration)

The PowerAuthSharingConfiguration object contains the following properties:

• appGroup is the name of the app group shared between your applications. Be aware, that the length of app group encoded in UTF-8, should not exceed 26 characters. See troubleshooting section for more details.
• appIdentifier is an identifier unique across all your applications or extensions that are supposed to use the shared activation data. You can use your applications’ bundle identifiers or any other identifier that can be then identified in all your applications (such as smartBank, smartBank.walletExt, investmentsApp, etc.) Due to technical limitations, the length of the identifier must not exceed 127 bytes, if represented in UTF-8.
• keychainAccessGroup is an access group for keychain sharing.

External pending operations

Some operations, such as the activation process, must be exclusively finished in the application that initiated the operation. For example, if you start an activation process in one app, then all other applications that use the same shared activation data may receive a failure with the PowerAuthErrorCode.externalPendingOperation error code until the operation is finished. To prevent such errors you can determine this state in advance:

if let externalOperation = powerAuthSDK.externalPendingOperation {
    print("Application \(externalOperation.externalApplicationId) already started \(externalOperation.externalOperationType)")
}

The same PowerAuthExternalPendingOperation object can be also extracted from the NSError error. For example:

powerAuthSDK.createActivation(activation) { (result, error) in
    if let error = error {
        if let externalOperation = error.powerAuthExternalPendingOperation {
            print("Application \(externalOperation.externalApplicationId) already started \(externalOperation.externalOperationType)")
        }
    }
}

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