.NET SDK reference (client-side)

Overview

This topic documents how to get started with the client-side .NET SDK, and links to reference information on all of the supported features.

Getting started

After you complete the Getting started process, follow these instructions to start using the LaunchDarkly SDK in your application.

To start using the client-side .NET SDK:

Install-Package LaunchDarkly.ClientSdk
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Next, import the LaunchDarkly packages in your application code:

using LaunchDarkly.Sdk;
using LaunchDarkly.Sdk.Client;
// LaunchDarkly.Sdk defines general types like User, which are also used in the server-side .NET SDK.
// LaunchDarkly.Sdk.Client defines the LdClient and Configuration types for the client-side .NET SDK.
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After you install the dependency, initialize the LaunchDarkly client by creating a single, shared instance of LdClient. To create a client instance, you need your environment's mobile key. This authorizes your application to connect to a particular environment within LaunchDarkly. Your mobile key is available in the Projects tab of your Account settings page. Mobile keys are not secret and you can expose them in your client-side code without risk. Never embed a server-side SDK key into a client-side application.

The following example shows the simplest way to create the client. It blocks for up to one second until it retrieves the latest feature flags from LaunchDarkly.

Here's how:

var user = User.WithKey(user_key);
var timeSpan = TimeSpan.FromSeconds(10);
client = LdClient.Init("MY_MOBILE_KEY", user, timeSpan);
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However, calling blocking code from the main thread in a mobile app is not considered a best practice. The preferred method is to load the client asynchronously.

Here's how:

User user = User.WithKey(user_key);
client = await LdClient.InitAsync("MY_MOBILE_KEY", user);
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You can use client to check which variation a particular user will receive for a given feature flag.

Here's how:

bool showFeature = client.BoolVariation("your.feature.key", false);
if (showFeature) {
    // Application code to show the feature
}
else {
    // The code to run if the feature is off
}
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Using the Relay Proxy

You can configure the client-side .NET SDK to connect to the Relay Proxy as follows:

Configuration config = Configuration.Builder("YOUR_SDK_KEY")
    .ServiceEndpoints(
        Components.ServiceEndpoints().RelayProxy("YOUR_RELAY_URI")
    )
    .Build();
LdClient client = LdClient.Init(config);
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Shutting down

Shut down the client when your application terminates. To learn more, read Shutting down.

Data collection

To learn more about data collection within this SDK and implications on submissions to the Apple App Store, read the Apple App Store data collection policy.

Supported features

This SDK supports the following features:

• Aliasing users
• Configuration
• Evaluating flags
• Flag evaluation reasons
• Flushing events
• Getting all flags
• Identifying and changing users
• Logging configuration
• Monitoring SDK status
• Offline mode
• Relay Proxy configuration, using proxy mode
• Sending custom events
• Shutting down
• Subscribing to flag changes
• Test data sources
• User configuration
• Web proxy configuration