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OCFeatureFlagManager and OCFeatureFlagSyncManager

Overview​

The OCFeatureFlagManager and OCFeatureFlagSyncManager are components designed to manage and synchronize feature flags in your application. Feature flags allow you to enable or disable specific functionality dynamically, making it easier to roll out new features, perform A/B testing, or toggle features based on user or environment conditions.

  • OCFeatureFlagManager: Handles local storage, overrides, and persistence of feature flags.
  • OCFeatureFlagSyncManager: Synchronizes feature flags with a remote API, ensuring your application stays up-to-date with the latest feature flag configurations.

OCFeatureFlagManager​

Description​

The OCFeatureFlagManager is responsible for managing feature flags locally. It provides functionality to save, load, override, and reset feature flags, as well as retrieve their effective values.

Key Features​

  • Persistence: Save and load feature flags using local storage.
  • Overrides: Temporarily override feature flag values.
  • Effective Values: Automatically prioritize override values over default values.
  • ETag Support: Track changes using ETags for efficient updates.

Protocol​

The OCFeatureFlagManagerProtocol defines the functionality of a feature flag manager:

public protocol OCFeatureFlagManagerProtocol {
    func saveFeatureFlags(_ flags: [String: OCRemoteFeatureFlag], etag: String?)
    func loadFeatureFlags()
    func getEtag() -> String?
    func getLastSaveTimestamp() -> TimeInterval?
    func overrideFeatureFlag(_ featureFlag: String, withValue value: Bool)
    func removeOverride(for featureFlag: String)
    func resetOverrides()
    func isEnabled(for featureFlag: String) -> Bool
    func savedFeatureFlags() -> [String: OCFeatureFlag]
    func isLocalStorageEmpty() -> Bool
}

Usage​

Saving Feature Flags​

await OCFeatureFlagManager.shared.saveFeatureFlags(flags, etag: "etag123")

Loading Feature Flags​

await OCFeatureFlagManager.shared.loadFeatureFlags()

Overriding a Feature Flag​

await OCFeatureFlagManager.shared.overrideFeatureFlag("featureFlagKey", withValue: true)

Removing an Override​

await OCFeatureFlagManager.shared.removeOverride(for: "featureFlagKey")

Resetting Overrides​

await OCFeatureFlagManager.shared.resetOverrides()

Retrieving a Feature Flag Value​

let value = OCFeatureFlagManager.shared.isEnabled(for: "featureFlagKey")

Checking if Local Storage is Empty​

let isEmpty = OCFeatureFlagManager.shared.isLocalStorageEmpty()

OCFeatureFlagSyncManager​

Description​

The OCFeatureFlagSyncManager is responsible for synchronizing feature flags with a remote API. It ensures that your application has the latest feature flag configurations by fetching them from a server.

Key Features​

  • Remote Synchronization: Fetch and update feature flags from a remote API.
  • ETag Support: Use ETags to optimize network requests and avoid unnecessary updates.

Usage​

Synchronizing Feature Flags​

let syncManager = OCFeatureFlagSyncManager(
    featureFlagManager: OCFeatureFlagManager.shared,
    networkManager: networkManager,
    featureFlagRequest: request
)
let success = await syncManager.synchronize()

Key Classes and Structs​

OCFeatureFlagManager​

Manages feature flags locally, including saving, loading, overriding, and resetting.

OCFeatureFlagSyncManager​

Synchronizes feature flags with a remote API.

OCFeatureFlag​

Represents a feature flag with its default value and optional override value.

public struct OCFeatureFlag: Codable {
    public var isEnabled: Bool
    public var displayName: String
    public var overrideValue: Bool?
    public var effectiveValue: Bool {
        overrideValue ?? isEnabled
    }

    public init(remoteFlag: OCRemoteFeatureFlag) {
        self.isEnabled = remoteFlag.enabled
        self.displayName = remoteFlag.displayName
    }
}

OCRemoteFeatureFlag​

Represents a feature flag fetched from a remote API.

public struct OCRemoteFeatureFlag: Codable {
    public var enabled: Bool
    public var displayName: String
}

Example Workflow​

  1. Save Feature Flags Locally:

    OCFeatureFlagManager.shared.saveFeatureFlags(flags, etag: "etag123")

  2. Synchronize with Remote API:

    let syncManager = OCFeatureFlagSyncManager(
        featureFlagManager: OCFeatureFlagManager.shared,
        networkManager: networkManager,
        featureFlagRequest: request
    )
    let success = await syncManager.synchronize()

  3. Override a Feature Flag:

    OCFeatureFlagManager.shared.overrideFeatureFlag("featureFlagKey", withValue: true)

  4. Retrieve Effective Value:

    let value = OCFeatureFlagManager.shared.isEnabled(for: "featureFlagKey")

  5. Reset Overrides:

    OCFeatureFlagManager.shared.resetOverrides()

Best Practices​

  • Keep Feature Flags Short-Lived: Remove unused feature flags to avoid clutter.
  • Use Meaningful Keys: Use descriptive keys for feature flags to improve readability.
  • Test Feature Flags: Ensure feature flags are tested in both enabled and disabled states.
  • Secure Remote API: Protect the API used for synchronization to prevent unauthorized access.

Conclusion​

The OCFeatureFlagManager and OCFeatureFlagSyncManager provide a robust solution for managing and synchronizing feature flags in your application. By leveraging these components, you can dynamically control application behavior, roll out features safely, and optimize user experiences.