Steps for A/B Testing Caffeine

Applying Caffeine to a percentage of user-sessions is supported. Because of a desire to change this percentage without submitting an update to the app store, this percentage value lives on a remote file that we control. The default value is 100%, so assuming a request is allowed and your license file is valid it will flow through Caffeine.
To change this percentage, please email our engineers at help@caffei.net

Determining whether Caffeine is enabled on the current session

Upon the start of every session, a notification whose name is stored as CaffeineHTTPProxy.caffeineInformationStringNotificationKey is posted to the default notification center. Within the notification's userInfo is a boolean value keyed by the same string-value as the notification name (right above) indicating whether or not Caffeine is enabled for the current session.

An Example View Controller

Swift 3:

import UIKit
import Proxeine

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        NotificationCenter.default.addObserver(self, selector: #selector(receivedCaffeineNotification(aNotification:)), name: NSNotification.Name(rawValue: CaffeineHTTPProxy.caffeineInformationStringNotificationKey), object: nil)
    }

    // Our method to receive the Caffeine notification
    func receivedCaffeineNotification(aNotification: NSNotification) {
        if aNotification.name.rawValue == CaffeineHTTPProxy.caffeineInformationStringNotificationKey {
            if let usingCaffeine = aNotification.userInfo?[CaffeineHTTPProxy.caffeineInformationStringNotificationKey] as? Bool {
                // 'usingCaffeine` now tracks whether Caffeine is enabled for this SESSION
                // You can log this value with your analytics service
            }
        }
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
    }
}

Your method for receiving the Notification can of course be anywhere in your project, but we strongly recommend adding the observer from within application:didFinishLaunchingWithOptions:

If at any time you require help, please contact our engineers at help@caffei.net. They're more than happy to help!