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Quickstart

The Eppo iOS SDK enables feature flags and experiments in your iOS applications with just a few lines of code. It handles flag evaluation and experiment assignments locally on the device, making it fast and reliable for your users.

Installation​

While in XCode:

  1. Choose Package Dependencies
  2. Click + and enter package URL: git@github.com:Eppo-exp/eppo-ios-sdk.git
  3. Set dependency rule to Up to Next Minor Version and select Add Package
  4. Add to your project's target.

Feature Flags​

Feature flags are a way to toggle features on and off without needing to deploy code.

Initialize the SDK​

First, initialize the SDK with your API key. You'll need to do this early in your application lifecycle:

import EppoFlagging

Task {
    try await EppoClient.initialize(sdkKey: "SDK-KEY-FROM-DASHBOARD");
}
tip

Get your SDK key from the Eppo web interface.

Make Assignments​

Once initialized, you can start using feature flags anywhere in your app:

let eppoClient = EppoClient.shared()

// Check if a feature should be enabled
let userId = getCurrentUserId() // Your user identification logic
var attributes = ["userType": "premium", "country": "US"]

let isEnabled = try eppoClient.getBooleanAssignment(
    flagKey: "new-feature",
    subjectKey: userId,
    subjectAttributes: attributes,
    defaultValue: false
)

if isEnabled {
    // Show new feature
    showNewFeature()
} else {
    // Show existing feature
    showExistingFeature()
}

Running Experiments​

To run experiments, you'll need to add a logging callback during initialization to track assignments:

// Example of a simple assignmentLogger function
func segmentAssignmentLogger(assignment: Assignment) {
    let assignmentDictionary: [String: Any] = [
        "allocation": assignment.allocation,
        "experiment": assignment.experiment,
        "featureFlag": assignment.featureFlag,
        "variation": assignment.variation,
        "subject": assignment.subject,
        "timestamp": assignment.timestamp
    ]

    analytics.track(
        name: "Eppo Assignment", 
        properties: TrackProperties(assignmentDictionary)
    )
}

eppoClient = try await EppoClient.initialize(sdkKey: "<SDK-KEY>", assignmentLogger: segmentAssignmentLogger)

Then use the SDK to make experiment assignments:

let assignment = try eppoClient.getStringAssignment(
    flagKey: "new-user-onboarding",
    subjectKey: user.id,
    subjectAttributes: user.attributes,
    defaultValue: "control"
);

// Use the variant value to determine which component to render
if assignment == "version-a" {
    showVersionA()
} else if assignment == "version-b" {
    showVersionB()
} else {
    showControl()
}

Next Steps​

Now that you have the basics working, here are some advanced topics to explore: