Set up iOS SDK

import LaunchDarkly

// This is your mobile key.
let config = LDConfig(mobileKey: "YOUR_MOBILE_KEY", autoEnvAttributes: .enabled)

// A "context" is a data object representing users, devices, organizations, and other entities.
let contextBuilder = LDContextBuilder(key: "EXAMPLE_CONTEXT_KEY")
guard case .success(let context) = contextBuilder.build()
else { return }

LDClient.start(config: config, context: context, startWaitSeconds: 5) { timedOut in
    if timedOut {
        print("SDK didn't initialize in 5 seconds.  SDK is still running and trying to get latest flags.")
    } else {
        print("SDK successfully initialized with the latest flags")
    }
}

print("SDK started.")

import LaunchDarkly

// Call this once from your app startup (e.g. application(_:didFinishLaunchingWithOptions:)).
// You can't invoke LDClient.start() at the top level in Swift — wrap it in a function.
func startLaunchDarkly() {
    // This is your mobile key.
    let config = LDConfig(mobileKey: "YOUR_MOBILE_KEY", autoEnvAttributes: .enabled)

    // A "context" is a data object representing users, devices, organizations, and other entities.
    var contextBuilder = LDContextBuilder(key: "EXAMPLE_CONTEXT_KEY")
    contextBuilder.trySetValue("email", .string("EXAMPLE_EMAIL"))
    guard case .success(let context) = contextBuilder.build() else { return }

    LDClient.start(config: config, context: context, startWaitSeconds: 5) { timedOut in
        if timedOut {
            print("SDK didn't initialize in 5 seconds. SDK is still running and trying to get latest flags.")
        } else {
            print("SDK successfully initialized with the latest flags")
        }
    }
}

// Call trackMetric when a metric action occurs in your app —
// a tap, a form submit, a screen view, a custom event, whatever your metric measures.
func trackMetric(metricKey: String, data: LDValue = .null) {
    let client = LDClient.get()!
    client.track(key: metricKey, data: data)
}