Flutter SDK reference

Overview

This topic documents how to get started with the Flutter 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 Flutter mobile application.

First, declare a dependency on the LaunchDarkly Flutter SDK:

launchdarkly_flutter_client_sdk: ^2.0.0
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Then, import the package in your application code:

import 'package:launchdarkly_flutter_client_sdk/launchdarkly_flutter_client_sdk.dart';
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After you install the SDK, initialize the 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.

The following example shows the simplest way to create the client:

LDConfig config = LDConfigBuilder('mobile-key-123abc').build();
LDContextBuilder builder = LDContextBuilder();
builder.kind('user', 'user-key-123abc');
LDContext context = builder.build();
await LDClient.startWithContext(config, context);
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This method of initializing the client lets you use the SDK as soon as it is ready to return evaluated flags.

To block until the SDK receives the most recent feature flag values, use the LDClient.startFuture method with await and an optional timeLimit:

LDConfig config = LDConfigBuilder('mobile-key-123abc').build();
LDContextBuilder builder = LDContextBuilder();
builder.kind('user', 'user-key-123abc');
LDContext context = builder.build();
await LDClient.startWithContext(config, context);
await LDClient.startFuture(timeLimit: Duration(seconds: 5));
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If you have configured the SDK not to make network requests, or if the device does not have a network connection, LDClient.startFuture returns a Future that will complete immediately to avoid blocking the application indefinitely.

You can use LDClient to check which variation a particular context will receive for a feature flag.

Here's how:

bool showFeature = await LDClient.boolVariation(flagKey, false);
if (showFeature) {
    // Application code to show the feature
}
else {
    // The code to run if the feature is off
}
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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:

• Anonymous contexts and users
• Configuration, including
  • Application metadata configuration
  • Service endpoint configuration
• Evaluating flags
• Flag evaluation reasons
• Flushing events
• Getting all flags
• Identifying and changing contexts
• Monitoring SDK status
• Offline mode
• Private attributes
• Relay Proxy configuration, using proxy mode
• Sending custom events
• Shutting down
• Subscribing to flag changes
• User and context configuration