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iOS SDK for Statsig

Statsig client SDK for iOS applications. This SDK is open source and hosted on github.

The Basics#

Get started in a few quick steps.

  1. Create a free account on statsig.com
  2. Install the SDK
  3. Initialize the SDK
  4. Fetch Feature Gates, Dynamic Configs, or Experiments
  5. Log a custom event

Step 1 - Create a free account on www.statsig.com#

You could skip this for now, but you will need an SDK Key and some Feature Gates or Dynamic Configs to use with the SDK in just a minute.

Step 2 - Install the SDK#

To install the SDK in your project, you can add Statsig as a dependency through Swift Package Manager: in your Xcode, select File > Swift Packages > Add Package Dependency and enter the URL https://github.com/statsig-io/ios-sdk.git.

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

//...
dependencies: [
// see the latest version on https://github.com/statsig-io/ios-sdk/releases
.package(url: "https://github.com/statsig-io/ios-sdk.git", .upToNextMinor("1.5.0")),
],
//...
targets: [
.target(
name: "YOUR_TARGET",
dependencies: ["Statsig"]
)
],
//...

If you are using CocoaPods, our pod name is 'Statsig', and you can include the following line to your Podfile:

use_frameworks!
target 'TargetName' do
//...
pod 'Statsig', '~> 1.5.0' // Add this line, see the latest version on https://github.com/statsig-io/ios-sdk/releases
end

Step 3 - Initialize the SDK#

After installation, you will need to initialize the SDK using a Client SDK key from the "API Keys" tab on the Statsig console.

These Client SDK Keys are intended to be embedded in client side applications. If need be, you can invalidate or create new SDK Keys for other applications/SDK integrations.

info

Do NOT embed your Server Secret Key in client side applications

In addition to the SDK key, you should also pass in a Statsig user for feature gate targeting and experimentation grouping purposes.

The 3rd parameter is optional and allows you to pass in a StatsigOptions to customize the SDK.

Statsig.start(
sdkKey: "my_client_sdk_key",
user: StatsigUser(userID: "my_user_id"),
options: StatsigOptions(environment: StatsigEnvironment(tier: .Staging)))
{ errorMessage in
// Statsig client is ready; you can also check errorMessage for any debugging information.
}

The completion block is called after initialization has completed.

Step 4 - Fetch Feature Gates, Dynamic Configs, or Experiments#

Now that your SDK is initialized, let's fetch a Feature Gate. Feature Gates can be used to create logic branches in code that can be rolled out to different users from the Statsig Console. Gates always CLOSED or OFF (think return false;) by default.

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

Feature Gates can be very useful for simple on/off switches, with optional but advanced user targeting. However, if you want to be able send a different set of values (strings, numbers, and etc.) to your clients based on specific user attributes, e.g. country, Dynamic Configs can help you with that. The API is very similar to Feature Gates, but you get an entire json object you can configure on the server and you can fetch typed parameters from it. 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)

Then we have Experiments, which you can use to run A/B/n experiments and use advanced features like layers (coming soon) to avoid collision and enable quicker iterations with parameter reuse.

let expConfig = Statsig.getExperiment("new_user_promo")
let promoTitle = expConfig.getValue(forKey: "title", defaultValue: "Welcome to Statsig! Use discount code WELCOME10OFF for 10% off your first purchase!")
let discount = expConfig.getValue(forKey: "discount", defaultValue: 0.1)
...
let price = msrp * (1 - discount);

Step 5 - Log a custom event#

Now that you have a Feature Gate or an Experiment set up, you may want to track some custom events and see how your new features or different experiment groups affect these events. This is super easy with Statsig - simply call the Log Event API for the event, and you can additionally provide some value and/or an object of metadata to be logged together with the event:

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

Statsig User#

You should provide a StatsigUser object whenever possible when initializing the SDK, passing as much information as possible in order to take advantage of advanced gate and config conditions (like country or OS/browser level checks). Most of the time, the userID field is needed in order to provide a consistent experience for a given user (see logged-out experiments to understand how to correctly run experiments for logged-out users). If the user is logged out at the SDK init time, you can leave the userID out for now, and we will use a stable device ID that we create and store in the local storage for targeting purposes.

Besides userID, we also have email, ip, userAgent, country, locale and appVersion as top-level fields on StatsigUser. In addition, you can pass any key-value pairs in an object/dictionary to the custom field and be able to create targeting based on them.

Once the user logs in or has an update/changed, make sure to call updateUser with the updated userID and/or any other updated user attributes:

let newUser = StatsigUser(userID: "new_user_id", email: "newUser@gmail.com", country: "US")
Statsig.updateUser(newUser) { errorMessage in
// Statsig has fetched the values for the new user
}

Have sensitive user PII data that should not be logged?#

No problem, we have a solution for it! On the StatsigUser object we also have a field called privateAttributes, which is a simple object/dictionary that you can use to set private user attributes. Any attribute set in privateAttributes will only be used for evaluation/targeting, and removed from any logs before they are sent to Statsig server.

For example, if you have feature gates that should only pass for users with emails ending in "@statsig.com", but do not want to log your users' email addresses to Statsig, you can simply add the key-value pair { email: "my_user@statsig.com" } to privateAttributes on the user and that's it!

Statsig Options#

Statsig.start() takes an optional parameter options in addition to sdkKey and user that you can provide to customize the Statsig client. Here are the current options and we are always adding more to the list:

  1. initTimeout: double, default 3.0
    • used to decide how long the Statsig client waits for the initial network request to respond before calling the completion block. The Statsig client will return either cached values (if any) or default values if checkGate/getConfig/getExperiment is called before the initial network request completes.
    • If you always want to wait for the latest values fetched from Statsig server, you should set this to 0 so we do not timeout the network request.
  2. disableCurrentVCLogging: boolean, default false
    • by default, any custom event your application logs with Statsig.logEvent() includes the current root View Controller. This is so we can generate user journey funnels for your users. You can set this parameter to true to disable this behavior.
  3. environment: StatsigEnvironment, default nil
    • StatsigEnvironment is a class for you to set environment variables that apply to all of your users in the same session and will be used for targeting purposes.
    • e.g. passing in a value of StatsigEnvironment(tier: .Staging) will allow your users to pass any condition that pass for the staging environment tier, and fail any condition that only passes for other environment tiers.
  4. enableAutoValueUpdate: boolean, default false
    • by default, feature values for a user is fetched once during Statsig.start and don't change throughout the session. Setting this value to true will turn on the feature for Statsig to periodically fetch updated values for the current user.

Shutting down Statsig#

In order to save users' data and battery usage, as well as prevent logged events from being dropped, we keep event logs in client cache and flush periodically. Because of this, some events may not have been sent when your app shuts down. To make sure all logged events are properly flushed or saved locally, you should tell Statsig to shutdown when your app is closing:

Statsig.shutdown()

FAQ#

How do I run experiments for logged out users?#

(Coming soon)