iOS SDK reference

Overview

This topic documents how to get started with the iOS 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:

• Including the SDK as a dependency
• Importing the SDK
• Initializing the SDK

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. Each method is explained below.

//...
    dependencies: [
        .package(url: "https://github.com/launchdarkly/ios-client-sdk.git", .upToNextMinor("9.0.0")),
    ],
    targets: [
        .target(
            name: "YOUR_TARGET",
            dependencies: ["LaunchDarkly"]
        )
    ],
//...
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use_frameworks!
target 'YourTargetName' do
  pod 'LaunchDarkly', '~> 9.0'
end
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github "launchdarkly/ios-client" ~> 9.0
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Importing the SDK

After you install the SDK as a dependency, import the LaunchDarkly client in your application code:

import LaunchDarkly
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Initializing the SDK

After importing the SDK, configure and initialize it. Specify your mobile key when configuring the SDK so that your application is authorized to connect to a particular environment within LaunchDarkly.

The following example shows how to configure the SDK, specify your mobile key, and initialize the client. The start() call to initialize the client executes asynchronously, to avoid blocking the main thread. If you need to ensure that the most recent flags have been received, start() supports an optional completion that is triggered when the SDK has retrieved flags for the configured context.

Here's how:

let config = LDConfig(mobileKey: "mobile-key-123abc", autoEnvAttributes: .enabled)
let context = LDContextBuilder(key: "context-key-123abc")
LDClient.start(config: config, context: context) {
  // Client has received flags for the context
}
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You can also choose to execute code either as soon as flags have been retrieved, or after a set amount of time, whichever comes first. This sets a maximum waiting period for establishing the connection. The following example uses five seconds. The SDK provides a timedOut boolean for the completion closure, indicating whether the connection timed out.

Here's how:

let config = LDConfig(mobileKey: "mobile-key-123abc", autoEnvAttributes: .enabled)
let context = LDContextBuilder(key: "context-key-123abc")
LDClient.start(config: config, context: context, startWaitSeconds: 5) { timedOut in
    if timedOut {
        // Client may not have the most recent flags for the configured context
    } else {
        // Client has received flags for the configured context
    }
}
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To learn more about the specific configuration options available in this SDK, read LDConfig.

After calling start, you can retrieve the LDClient instance with the static method LDClient.get():

let client = LDClient.get()!
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Then, use the client to check which variation a particular context will receive for a given feature flag.

Here's how:

let showFeature = client.boolVariation(forKey: "flag-key-123abc", defaultValue: false)
if showFeature {
  // Application code to show the feature
else {
  // The code to run if the feature is off
}
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Background fetch

When the app is backgrounded, the SDK does not receive real-time events.

Unlike other mobile SDKs, the iOS SDK does not support background fetch, so devices on the iOS operating system will not fetch flags from the background. However, devices on MacOS will update flag values opportunistically, according to the iOS SDK standard background polling defaults.

To change the background polling default for flags in your app, add the following code in your LDConfig:

var ldConfig = LDConfig(mobileKey: "mobile-key-123abc", autoEnvAttributes: .enabled)
ldConfig.backgroundFlagPollingInterval = 3600
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Shut down the client

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

Data collection

The data collected by the iOS SDK persists until the number of cached contexts exceeds a limit. When you call identify, the number of cached contexts increments. Eventually, the number of cached contexts exceeds maxCachedContexts. When that happens, the SDK deletes context data in excess of maxCachedContext, starting with the oldest context first.

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