Consent Management by data categories in mobile app

Implementing Consent Management by Data Categories in Mobile Apps

Consent Management is not just one "I agree" button. It's a system tracking exactly what user consented to, when, under what document version, and what to do if revoked.

Without this system impossible to comply with GDPR/CCPA or prove compliance at audit.

Why Single "Accept" Insufficient

Regulators require granular consent: user must be able to consent to analytics but refuse advertising profiling. Forcing accept-all or nothing — violates free choice principle per GDPR. ICO (UK) and CNIL (France) already fined for this.

Technically means: separate boolean per category, not single consent_accepted field.

Consent Manager Architecture

enum class ConsentPurpose(val id: String) {
    NECESSARY("necessary"),
    ANALYTICS("analytics"),
    MARKETING("marketing"),
    PERSONALIZATION("personalization"),
    THIRD_PARTY_SHARING("third_party_sharing"),
    LOCATION_TRACKING("location_tracking"),
    PUSH_MARKETING("push_marketing")
}

data class ConsentRecord(
    val purpose: ConsentPurpose,
    val granted: Boolean,
    val grantedAt: Long?,         // null if not granted
    val revokedAt: Long?,         // null if not revoked
    val policyVersion: String,    // policy version consent given under
    val collectionMethod: String  // "explicit_ui", "imported", "default_opt_in"
)

class ConsentManager(
    private val store: ConsentStore,
    private val server: ConsentSyncService
) {

    fun grant(purpose: ConsentPurpose) {
        val record = ConsentRecord(
            purpose = purpose,
            granted = true,
            grantedAt = System.currentTimeMillis(),
            revokedAt = null,
            policyVersion = PolicyVersionProvider.current(),
            collectionMethod = "explicit_ui"
        )
        store.save(record)
        server.syncAsync(record)
        notifySDKs(purpose, granted = true)
    }

    fun revoke(purpose: ConsentPurpose) {
        val existing = store.get(purpose)?.copy(
            granted = false,
            revokedAt = System.currentTimeMillis()
        ) ?: return

        store.save(existing)
        server.syncAsync(existing)
        notifySDKs(purpose, granted = false)
    }

    fun isGranted(purpose: ConsentPurpose): Boolean {
        return store.get(purpose)?.granted == true
    }
}

SDK Synchronization

On consent change — immediately update affected SDKs:

private fun notifySDKs(purpose: ConsentPurpose, granted: Boolean) {
    when (purpose) {
        ANALYTICS -> {
            FirebaseAnalytics.getInstance(context)
                .setAnalyticsCollectionEnabled(granted)
            amplitude.setOptOut(!granted)
        }
        MARKETING -> {
            MobileAds.setRequestConfiguration(
                RequestConfiguration.Builder()
                    .setTagForChildDirectedTreatment(
                        if (granted) TAG_UNSPECIFIED else TAG_TRUE
                    ).build()
            )
        }
        PUSH_MARKETING -> {
            if (!granted) {
                // Unsubscribe from marketing FCM topics
                FirebaseMessaging.getInstance()
                    .unsubscribeFromTopic("marketing_campaigns")
            }
        }
        else -> {}
    }
}

Consent Management Screen

Available from profile settings anytime — not just on first launch. Structure:

Data Management
├── Necessary (non-togglable)
│   └── Authentication and Security
├── Usage Analytics           [ON] ←→
│   └── Helps us improve app
├── Personalization           [OFF] ←→
│   └── Recommendations based on your actions
├── Marketing Communications  [OFF] ←→
│   └── Email and push about news
└── Partner Sharing           [OFF] ←→
    └── Ad networks and analytics

Consent revocation works immediately. Can't add friction ("Sure?" → "Really sure?") — this is dark pattern.

Re-obtaining Consent

When new Privacy Policy version releases — assess whether changes affect prior consent. If new processing category added — need fresh consent for it. If just wording changes without substance change — notification sufficient.

Mechanism: on app startup check policyVersion in stored consent records. If outdated — show updated screen only for changed categories.

Storage and Audit

Consent records can't be deleted on account deletion — needed to prove compliance at check. Stored separately from user data, retention per requirements (usually 5–7 years for legally significant documents).

Timeline: full Consent Management system with UI, SDK orchestration and server sync: 2–3 days. Cost calculated individually.