iOS SDK reference

This reference guide documents all of the methods available in the iOS SDK, and explains in detail how these methods work. If you want to dig even deeper, our SDKs are open source. To learn more, view the source on the iOS SDK GitHub repository or the generated API docs. Additionally you can clone and run sample applications using this SDK with iOS, macOS, and tvOS.

Getting started

Building on top of our Getting Started guide, the following steps will get you started with using the LaunchDarkly SDK in your application.

Including the SDK as a dependency

The first step is to install the LaunchDarkly SDK as a dependency in your application. LaunchDarkly supports multiple methods for installing the SDK in your application.

Swift Package Manager

If you use the Swift Package Manager, you can install the SDK through Xcode or include it as a dependency in your Package.swift file.

To add a package dependency to your Xcode project, select File > Swift Packages > Add Package Dependency and enter the iOS SDK repository URL clone URL, then select your desired version constraints.

Including the SDK as a dependency in a Package.swift file would look like this:

1//...
2    dependencies: [
3        .package(url: "https://github.com/launchdarkly/ios-client-sdk.git", .upToNextMinor("5.4.0")),
4    ],
5    targets: [
6        .target(
7            name: "YOUR_TARGET",
8            dependencies: ["LaunchDarkly"]
9        )
10    ],
11//...
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CocoaPods

If you use CocoaPods, you can install the SDK by adding the following to your Podfile. Refer to the SDK releases page to identify the latest version.

1use_frameworks!
2target 'YourTargetName' do
3  pod 'LaunchDarkly', '~> 5.4'
4end
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Carthage

If you use Carthage, you can install the SDK by specifying it in your Cartfile. Again, refer to the SDK releases page to identify the latest version.

1github "launchdarkly/ios-client" ~> 5.4
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Installing the SDK manually

Refer to the SDK readme for instructions on installing the SDK without CocoaPods or Carthage.

Using the SDK in your application

This is a brief overview of using the SDK, see the detailed sections below for more information on configuration and advanced features.

Importing

First import the LaunchDarkly client in your application code.

1import LaunchDarkly
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Initializing the SDK

Now that the SDK is imported, it can be configured and initialized. You should specify your mobile key when configuring the SDK so that your application will be authorized to connect to LaunchDarkly, retrieve flags for your environment, and report events.

1let config = LDConfig(mobileKey: "YOUR_MOBILE_KEY")
2let user = LDUser(key: "test-user")
3
4LDClient.start(config: config, user: user)
5
6// If you need to ensure that the most recent flags have been received
7// start supports an optional completion that is triggered when the SDK
8// has retrieved flags for the configured user.
9LDClient.start(config: config, user: user) {
10    // Client has received flags for the user
11}
12
13// If you would like the completion to be called even in cases where
14// the SDK is unable to retrieve flags for the user, there is a variant
15// to the start method that takes a maximum time to wait for flag values.
16// This variant notifies the completion whether the operation timed out.
17LDClient.start(config: config, user: user, startWaitSeconds: 5) { timedOut in
18    if timedOut {
19        // The SDK may not have the most recent flags for the configured user
20    } else {
21        // The SDK has received flags for the configured user
22    }
23}
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Retrieving the client instance

After calling start, the LDClient instance can be retrieved with the static method LDClient.get().

1let ldClient = LDClient.get()!
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Getting the variation to serve the configured user

Using the LDClient instance, you can check which variation the configured user should receive for a given feature flag.

1let showFeature = ldClient.variation(forKey: "flag-key", defaultValue: false)
2
3if showFeature {
4  // application code to show the feature
5else {
6  // the code to run if the feature is off
7}
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Terminating the client instance

Lastly, when your application is about to terminate, shut down the LDClient instance. This ensures that the client releases any resources it is using, and that any pending analytics events are delivered to LaunchDarkly. If your application quits without this shutdown step, you may not see your requests and users on the dashboard, because they are derived from analytics events. This is something you only need to do one time.

1ldClient.close()
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Background fetch

When the app is backgrounded, the SDK does not receive real-time events. However, MacOS supports background fetch which updates flag values opportunistically, according to iOS standard defaults. iOS does not support background fetch.

To change the background fetch interval for flags in your app, add the following code in your LDConfig:

1var ldConfig = LDConfig(mobileKey: "MY_MOBILE_KEY")
2ldConfig.backgroundFlagPollingInterval = 3600
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Data collection

To learn more about data collection within this SDK and implications on submissions to the Apple App Store, read 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
• Monitoring SDK status
• Multiple environments
• Offline mode
• Sending custom events
• Subscribing to flag changes
• User configuration