I compared iOS sdk with Android sdk and noticed that in iOS sdk isn't provided the ability to send additional context data with application lifecycle. In Android sdk clearly stated that: To send additional context data with your lifecycle call by using Config.collectLifecycleData(Activity activity, Map<String, Object> contextData), you must override the onResume method for that Activity and ensure that you call super.onResume() after manually calling collectLifecycleData.
To include additional data with lifecycle metric calls, use collectLifecycleDataWithAdditionalData:
Important: Any data that is passed to the SDK through collectLifecycleDataWithAdditionalData: will be persisted in NSUserDefaults by the SDK. The SDK strips the values in the NSDictionary parameter that are not of the NSString or NSNumber types.
Along with this, you will need to add the same collectLifecycleDataWithAdditionalData code into iOS applicationWillEnterForeground method as well. This is the part that helps send the additional data layer variables on the subsequent lifecycle calls after the first one.