---
title: OptimizelyConfig for the Swift SDK
slug: feature-experimentation/docs/optimizelyconfig-swift
docTags: 
createdAt: 2026-08-05T20:39:51.000Z
---

Optimizely Feature Experimentation SDKs open a well-defined set of public APIs, hiding implementation details. However, you may need access to project configuration data within the [datafile](docId:3LmHm4b3kTxKBuoR93KN8). The following section extends the public APIs to define data models and access methods, which you can use to access project configuration data.

A public configuration data model (OptimizelyConfig) is defined as a structured format of static Optimizely Project data.

### Get `OptimizelyConfig`

You can access `OptimizelyConfig` through the `OptimizelyClient` (top-level) using this public API call.

```swift
public func getOptimizelyConfig() throws -> OptimizelyConfig
```

`getOptimizelyConfig` returns an `OptimizelyConfig` instance, which includes the following:

- Environment key
- SDK key
- Datafile revision number
- Experiments mapped by key values
- All attributes
- All audiences
- All events
- Feature flags mapped by key values

:::hint{type="info"}
When the system updates the datafile, you can add a [OptimizelyConfigUpdate notification listener](#)  to get notified. After receiving the notification, call the method to get the updated `OptimizelyConfig` data.
:::

### Get datafile

To share the same datafile between multiple SDK instances, such as in a client and server scenario, you can pass a JSON string representation of the config (the datafile) between the instances. The Swift SDK's `OptimizelyConfig` does not expose the datafile. To get the datafile at initialization, use the `Data` in the `.success` result of `start(completion:)`. To get later datafile updates, add a `datafileChange` notification listener (`notificationCenter?.addDatafileChangeNotificationListener { data in ... }`). The listener fires only when a background fetch returns a new revision, not on initialization. For information, see [Sharing the datafile with multiple SDK implementations](docId\:eH-UMm_rOn_GdGDGLV6__).

### Object model

The following sample shows the object model for OptimizelyConfig:

```swift
public protocol OptimizelyConfig {
  var environmentKey: String { get }
  var sdkKey: String { get }
  var revision: String { get }
  
  // This experimentsMap is for experiments of legacy projects only.
  // For flag projects, experiment keys are not guaranteed to be unique 
  // across multiple flags, so this map may not include all experiments 
  // when keys conflict.
  var experimentsMap: [String: OptimizelyExperiment] { get }
  
  var featuresMap: [String: OptimizelyFeature] { get }
  var attributes: [OptimizelyAttribute] { get }
  var audiences: [OptimizelyAudience] { get }
  var events: [OptimizelyEvent] { get }
}

public protocol OptimizelyExperiment {
  var id: String { get }
  var key: String { get }
  var audiences: String { get }
  var variationsMap: [String: OptimizelyVariation] { get }
}

public protocol OptimizelyFeature {
  var id: String { get }
  var key: String { get }
  var experimentRules: [OptimizelyExperiment] { get }
  var deliveryRules: [OptimizelyExperiment] { get }
  var variablesMap: [String: OptimizelyVariable] { get }
    
  @available(*, deprecated, message: "Use experimentRules and deliveryRules instead")
  var experimentsMap: [String: OptimizelyExperiment] { get }
}

public protocol OptimizelyVariation {
  var id: String { get }
  var key: String { get }
  var featureEnabled: Bool? { get }
  var variablesMap: [String: OptimizelyVariable] { get }
}

public protocol OptimizelyVariable {
  var id: String { get }
  var key: String { get }
  var type: String { get }
  var value: String { get }
}

public protocol OptimizelyAttribute {
  var id: String { get }
  var key: String { get }
}

public protocol OptimizelyAudience {
  var id: String { get }
  var name: String { get }
  var conditions: String { get }
}

public protocol OptimizelyEvent {
  var id: String { get }
  var key: String { get }
  var experimentIds: [String] { get }
}
```

## Examples

You can access `OptimizelyConfig` from the `OptimizelyClient` (top-level) using the following example code:

```swift
let config = try! optimizelyClient.getOptimizelyConfig()

print("[OptimizelyConfig] revision = \(config.revision)")
print("[OptimizelyConfig] sdkKey = \(config.sdkKey)")
print("[OptimizelyConfig] environmentKey = \(config.environmentKey)")

print("[OptimizelyConfig] attributes:")
config.attributes.forEach { attribute in
    print("[OptimizelyAttribute]   -- (id, key) = (\(attribute.id), \(attribute.key))")
}
print("[OptimizelyConfig] audiences:")
config.audiences.forEach { audience in
    print("[OptimizelyAudience]   -- (id, name, conditions) = (\(audience.id), \(audience.name), \(audience.conditions))")
}
print("[OptimizelyConfig] events:")
config.events.forEach { event in
    print("[OptimizelyEvent]   -- (id, key, experimentIds) = (\(event.id), \(event.key), \(event.experimentIds))")
}

// all flags
let flags = config.featuresMap.values
let flagKeys = config.featuresMap.keys

for flagKey in flagKeys {
   let flag = config.featuresMap[flagKey]!

   let experimentRules = flag.experimentRules
   let deliveryRules = flag.deliveryRules
  
   // use experiment rules and delivery rules and other flag data here...
  
   experimentRules.forEach { experiment in
      print("[OptimizelyExperiment]   - experiment rule-key = \(experiment.key)")
      print("[OptimizelyExperiment]   - experiment audiences = \(experiment.audiences)")

      let variationsMap = experiment.variationsMap
      let variationKeys = variationsMap.keys
                
      variationKeys.forEach { varKey in
         let variation = variationsMap[varKey]!
         print("[OptimizelyVariation]       -- variation = { key: \(varKey), id: \(variation.id), featureEnabled: \(String(describing: variation.featureEnabled)) }")
                    
         let variablesMap = variationsMap[varKey]!.variablesMap
         let variableKeys = variablesMap.keys
                    
         variableKeys.forEach { variableKey in
            let variable = variablesMap[variableKey]!
                        
            print("[OptimizelyVariable]           --- variable: \(variableKey), \(variable)")
         }
      }
   }
  
   deliveryRules.forEach { delivery in
      print("[OptimizelyExperiment]   - delivery rule-key = \(delivery.key)")
      print("[OptimizelyExperiment]   - delivery audiences = \(delivery.audiences)")

      // use delivery rule data here...
   }
}

// listen to NotificationType.datafileChange to get updated data

_ = optimizelyClient.notificationCenter?.addDatafileChangeNotificationListener { _ in
   if let newOptConfig = try? optimizelyClient.getOptimizelyConfig() {
      print("[OptimizelyConfig] revision = \(newOptConfig.revision)")
   }
}
```