# Unity SDK

## Set up the SDK

{% steps %}
{% step title="Install the SDK" %}
The project is on [GitHub](https://github.com/statsig-io/unity-sdk). Add the package to your Unity project through **Package Manager** > **Add package from Git URL**, then enter `https://github.com/statsig-io/unity-sdk.git` (include the `.git` part in the URL).
{% /step %}

{% step title="Initialize the SDK" %}
Initialize the SDK with a client SDK key from the ["API Keys" tab on the Statsig console](https://console.statsig.com/api_keys). These keys are safe to embed in a client application.

Along with the key, pass in a [User Object](#statsig-user) with the attributes you'd like to target later on in a gate or experiment.

**Make all API calls to `Statsig` from the main thread.** Operations that take longer, such as network requests, run asynchronously and don't block the main thread.

```csharp
using StatsigUnity;

await Statsig.Initialize(
    "client-sdk-key",
    new StatsigUser { UserID = "some_user_id", Email = "user@email.com" },
    new StatsigOptions // optional parameters to customize your Statsig client, see "Statsig Options" section below to see details on available options
    {
        EnvironmentTier = EnvironmentTier.Development,
        InitializeTimeoutMs = 5000,
    }
);
```
{% /step %}
{% /steps %}

## Use the SDK

### Checking a Feature Flag/Gate

Now that your SDK is initialized, check a [**Feature Gate**](https://docs.statsig.com/feature-flags/overview). Feature Gates create logic branches in code that you can roll out to different users from the Statsig Console. Gates are always **CLOSED** or **OFF** (think `return false;`) by default.

```csharp
if (Statsig.CheckGate("show_new_loading_screen"))
{
  // Gate is on, show new loading screen
}
else
{
  // Gate is off, show old loading screen
}
```

### Reading a Dynamic Config

Feature Gates are useful for simple on/off switches with optional advanced user targeting. To send a different set of values (strings, numbers, etc.) to clients based on specific user attributes such as country, use **Dynamic Configs**. The API is similar to Feature Gates, but you get a complete JSON object you can configure on the server and fetch typed parameters from it. For example:

```csharp
var 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.
string itemName = config.Get<string>("product_name", "Awesome Product v1");
double price = config.Get<double>("price", 10.0);
bool shouldDiscount = config.Get<bool>("discount", false);
```

### Getting a Layer/Experiment

**Layers/Experiments** let you run A/B/n experiments. Statsig offers two APIs, but recommends [layers](https://docs.statsig.com/experiments/layers-overview) to enable quicker iterations with parameter reuse.

```csharp
// Values via getLayer

var layer = Statsig.GetLayer("user_promo_experiments");
var promoTitle = layer.Get("title", "Welcome to Statsig!");
var discount = layer.Get("discount", 0.1);

// or, via getExperiment

var titleExperiment = Statsig.GetExperiment("new_user_promo_title");
var priceExperiment = Statsig.GetExperiment("new_user_promo_price");

var promoTitle = titleExperiment.Get("title", "Welcome to Statsig!");
var discount = priceExperiment.Get("discount", 0.1);

...

double price = msrp * (1 - discount);
```

### Logging an event

After setting up a Feature Gate or Experiment, you may want to track custom events to see how new features or different experiment groups affect those events. Call the Log Event API for the event. You can also provide a value and metadata object to log with the event:

```csharp
Statsig.LogEvent(
  "purchase",
  "new_player_pack",
  new Dictionary<string, string>() {
    { "price", "9.99" }
  }
);
```

## Statsig User

You need to provide a StatsigUser object to check/get your configurations. Pass as much
information as possible to take advantage of advanced gate and config conditions.

Most of the time, you need the `userID` field to provide a consistent experience for a given
user (refer to [logged-out experiments](https://docs.statsig.com/guides/first-device-level-experiment) to understand how to correctly run experiments for logged-out
users).

Besides `userID`, Statsig also supports `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 create targeting based on them.

After the user logs in or their attributes change, call `updateUser` with the updated `userID` and any other updated user attributes:

```csharp
// if you want to update the existing user, or change to a different user, call UpdateUser.
// The API makes a network request to fetch values for the new user.

await Statsig.UpdateUser(
    new StatsigUser { UserID = "new_user_id", Email = "new_user@email.com" },
);
```

### Private attributes

To prevent logging sensitive user PII, use the `privateAttributes` field on the StatsigUser object. Statsig uses attributes set in `privateAttributes` only for evaluation and targeting, then removes them from any logs before sending them to the server.

For example, if you have feature gates that pass only for users with emails ending in "@statsig.com" but don't want to log your users' email addresses to Statsig, add the key-value pair `{ email: "my_user@statsig.com" }` to `privateAttributes` on the user.

## Statsig Options

`Initialize()` takes an optional parameter `options` in addition to `clientKey` and `user` that you can provide to customize the Statsig client.

{% parameter name="EnvironmentTier" type="EnvironmentTier" %}
Set the environment tier for the user. Values: `Production | Development | Staging`.
Statsig includes users with `null` or `Production` tier in Pulse metrics by default.
{% /parameter %}

{% parameter name="InitializeTimeoutMs" type="int" %}
Maximum milliseconds `Statsig.Initialize()` waits before proceeding with cached/default values.
{% /parameter %}

{% parameter name="LoggingIntervalMs" type="int" %}
Interval for periodically flushing logging events to the Statsig backend.
{% /parameter %}

{% parameter name="LoggingBufferMaxSize" type="int" %}
Maximum number of events the logger batches before flushing.
{% /parameter %}

## Shutting Statsig down

The SDK keeps event logs in client cache and flushes them periodically to save data and battery usage. Because the SDK flushes only periodically, it may not have flushed some events when your app shuts down.

To ensure the SDK flushes or saves all logged events locally, shut down Statsig when your app is closing:

```csharp
// This function is async, and you can choose to await for it so that we make sure all the
// events that are yet to be flushed get flushed
await Statsig.Shutdown();
```

## FAQs

#### How do I run experiments for logged out users

Refer to [Device-level experiments](https://docs.statsig.com/guides/first-device-level-experiment).