iOS/tvOS/macOS Client SDK

Set up the SDK

1. Install the SDK

   To use the SDK in your project, add Statsig as a dependency.

   Swift Package ManagerCocoapods

   In your Xcode, select File > Swift Packages > Add Package Dependency and enter the URL https://github.com/statsig-io/statsig-kit.git.

   You can also include it directly in your project's Package.swift. Find the latest release version on the GitHub page.

   swift

   Copy

   //...
   dependencies: [
       // see the latest version on https://github.com/statsig-io/statsig-kit/releases
       .package(url: "https://github.com/statsig-io/statsig-kit.git", .upToNextMinor("X.Y.Z")),
   ],
   //...
   targets: [
       .target(
           name: "YOUR_TARGET",
           dependencies: ["Statsig"]
       )
   ],
   //...
   

2. Initialize the SDK

   Initialize the SDK with a client SDK key from the "API Keys" tab on the Statsig console. These keys are safe to embed in a client application.Along with the key, pass in a User Object with the attributes you want to target later in a gate or experiment.

   SwiftObjective C

   Copy

   Statsig.initialize(
       sdkKey: "my_client_sdk_key",
       user: StatsigUser(userID: "my_user_id"),
       options: StatsigOptions(environment: StatsigEnvironment(tier: .Staging)))
   { error in
   
     // Statsig has finished fetching the latest feature gate and experiment values for your user.
     // If you need the most recent values, you can get them now.
   
     // You can also check error.message and error.code for any debugging information.
   
   }
   

   The SDK calls the completion block after the network request to fetch the latest feature gate and experiment values for your user. If you request any value before the SDK calls the completion block, you may get the cached value from the previous session or the default value. Wait for the completion block before requesting the latest value.

Use the SDK

Checking a Feature Flag/Gate

if Statsig.checkGate("new_homepage_design") {
  // Gate is on, show new home page
} else {
  // Gate is off, show old home page
}

Reading a Dynamic Config

Feature Gates work well for simple on/off switches with optional advanced user targeting. To send different values (strings, numbers, and similar types) to your clients based on specific user attributes such as country, use Dynamic Configs. The API is similar to Feature Gates but returns a full JSON object you can configure on the server and fetch typed parameters from. For example:

let config = Statsig.getConfig("awesome_product_details")

// The 2nd parameter is the default value to be used in case the given parameter name does not exist on
// the Dynamic Config object. This can happen when there is a typo, or when the user is offline and the
// value has not been cached on the client.
let itemName = config.getValue(forKey: "product_name", defaultValue: "Awesome Product v1")
let price = config.getValue(forKey: "price", defaultValue: 10.0)
let shouldDiscount = config.getValue(forKey: "discount", defaultValue: false)

Getting a Layer/Experiment

// Values via getLayer

let layer = Statsig.getLayer("user_promo_experiments")
let promoTitle = layer.getValue(forKey: "title", defaultValue: "Welcome to Statsig!")
let discount = layer.getValue(forKey: "discount", defaultValue: 0.1)

// or, via getExperiment

let titleExperiment = Statsig.getExperiment("new_user_promo_title")
let priceExperiment = Statsig.getExperiment("new_user_promo_price")

let promoTitle = titleExperiment.getValue(forKey: "title", defaultValue: "Welcome to Statsig")
let discount = priceExperiment.getValue(forKey: "discount", defaultValue: 0.1)

...

let price = msrp * (1 - discount);

Logging an Event

After you set up a Feature Gate or an Experiment, you can track custom events to measure how your new features or experiment groups affect those events. Call the Log Event API for the event, and optionally provide a value and/or a metadata object to log together with the event:

Statsig.logEvent(withName: "purchase", value: 2.99, metadata: ["item_name": "remove_ads"])

Parameter Stores

Statsig User

Provide a StatsigUser object to check or get your configurations. Pass as much information as possible to take advantage of advanced gate and config conditions.

Besides userID, the email, ip, userAgent, country, locale, and appVersion fields are also available as top-level fields on StatsigUser. You can also pass any key-value pairs in an object/dictionary to the custom field to create targeting based on them.

After the user logs in or their attributes change, call updateUserWithResult with the updated userID and/or any other updated user attributes.

let user = StatsigUser(
  userID: "a-user-id",
  email: "user@example.com",
  ip: "192.168.1.1",
  userAgent: "Mozilla/5.0",
  country: "US",
  locale: "en_US",
  appVersion: "1.0.0",
  custom: [
    "plan": "premium",
    "age": 25
  ],
  customIDs: [
    "stableID": "stable-id-123"
  ],
  privateAttributes: [
    "email": "private@example.com"
  ]
)

Statsig Options

   public enum EvaluationCallbackData {
      case gate (FeatureGate)
      case config (DynamicConfig)
      case experiment (DynamicConfig)
      case layer (Layer)
      case parameterStore (ParameterStore)
   }

    func callback(data: StatsigOptions.EvaluationCallbackData) {
       switch data {
       case .gate(let gate):
          // Handle gate evaluation
       case .config(let config):
          // Handle dynamic config evaluation
       case .experiment(let experiment):
          // Handle experiment evaluation
       case .layer(let layer):
          // Handle layer evaluation
       case .parameterStore(let paramStore):
          // Handle parameter store evaluation
       }
    }

    let opts = StatsigOptions(evaluationCallback: callback)
    Statsig.initialize(sdkKey: "client-key", options: opts)

   @objc public protocol StorageProvider {
      @objc func read(_ key: String) -> Data?
      @objc func write(_ value: Data, _ key: String)
      @objc func remove(_ key: String)
   }

   StatsigOptions(initializationURL: URL(string: "https://example.com/setup"))

   StatsigOptions(eventLoggingURL: URL(string: "https://example.com/info"))

StableID

Each client SDK has the concept of stableID: a device-level identifier generated the first time the SDK is initialized and stored locally for all future sessions. Unless storage is wiped (or the app is deleted), the stableID doesn't change. This allows Statsig to run device-level experiments and experiments when other user-identifiable information is unavailable (logged-out users).

let options = StatsigOptions(overrideStableID: "my_stable_id")
Statsig.initialize(sdkKey: "client-xyz", options: options)

Manual Exposures

You can query your gates/experiments without triggering an exposure and manually log the exposures later.

// Swift - Check without logging exposure
let result = Statsig.checkGateWithExposureLoggingDisabled("a_gate_name")
// ...
// Later, when ready to log the exposure
Statsig.manuallyLogGateExposure("a_gate_name")

Local Overrides

To locally override gates/configs/experiments/layers for testing, use the local override methods. Unless you call the remove method, these overrides persist session-to-session on the client's device. These overrides apply locally only and don't affect definitions in the console or elsewhere.

Shutting Statsig Down

To save users' data and battery usage and prevent logged events from being dropped, the SDK keeps event logs in client cache and flushes them periodically. Because of this, some events may not have been sent when your app shuts down.

To ensure all logged events are flushed or saved locally, call shutdown when your app is closing.

Statsig.shutdown()

Using multiple instances of the SDK

The examples above use the SDK's singleton. Statsig also supports creating multiple instances of the SDK. The Statsig singleton wraps a single instance of the SDK (typically called a StatsigClient) that you can instantiate directly.

All top-level static methods from the singleton carry over as instance methods. To create an instance of the Statsig SDK:

let client = StatsigClient(
    sdkKey: "client-xyz",
    user: StatsigUser(userID: "user-1"),
    options: StatsigOptions(environment: StatsigEnvironment(tier: .Production))
) { error in
  // ready
}

let gateOn = client.checkGate("some_gate")

Initialize Response

The SDK provides a method to access the raw values used internally for gate, config, and layer values. This is useful for debugging or for advanced use cases where you need to access the underlying data. For example, you can use these values to bootstrap another SDK, such as the JavaScript SDK when you open an in-app browser.

The getInitializeResponseJson method returns an ExternalInitializeResponse object that contains:

1. A JSON string representation of the initialize response values
2. Evaluation details that provide metadata about how the values were obtained (network, cache, etc.)

let response = Statsig.getInitializeResponseJson()
if let values = response.values {
    print(values)
}
let details = response.evaluationDetails

Listening for changes

In v1.14.0+, you can listen for SDK changes using StatsigListening.

class MyViewController: UIViewController, StatsigListening {

    override func viewDidLoad() {
        super.viewDidLoad()

        if Statsig.isInitialized() {
            render()
        } else {
            Statsig.addListener(self)
            renderLoading()
        }
    }

    private func render() {
        let showNewUI = Statsig.checkGate("new_ui_enabled")
        if showNewUI {
            // Render the new UI
        } else {
            // Render the old UI
        }
    }

    private func renderLoading() { /* loading UI */ }
    private func renderError(error: StatsigClientError) { /* error UI */ }

    // StatsigListening
    func onInitializedWithResult(_ error: StatsigClientError?) {
        if let error = error {
            renderError(error)
            return
        }
        render()
    }

    func onUserUpdatedWithResult(_ error: StatsigClientError?) { /* optional rerender */ }
}