Hi everyone. I've implemented GrowthBook into my tvOS Swift application, and feature flags work perfectly, but I'm having trouble getting experimentation to work. Whenever I create an experiment and do attribute targeting, the

trackingCallback

is never called, and the experiment doesn't work. The only way I can get it to work is by using the

user_uuid

attribute. Then the callback is called and the experiment works fine. I've tried creating many attribute types and seeing if they will match, but none work. Does anyone have any suggestions on what to do?

if let growthBook = growthBook {
            self.growthBook = growthBook
        } else {
            let builder = GrowthBookBuilder(
                apiHost: apiHost,
                clientKey: clientKey,
                attributes: [
                    // None of these work
                    "platform": "tvos", // enum attribute type
                    "platform_is_tv_tvos": true, // boolean type
                    "is_tvos": "true" // string type
                    // If I use the user_uuid experimentation works
//               "user_uuid": "3A662C6E-0A43-4BFB-B691-B25D685CD409"
                ],
                trackingCallback: { experiment, result in
                    print("[Debug] Experiment \(experiment.key) assigned variation \(result.variationId) with result \(result.value)")
                }
            )
            let sdk = builder.initializer()
            self.growthBook = GrowthBookSDKWrapper(sdk: sdk)
        }

Hi Fernando, That's because your identifier attribute is user_uuid. You have to have an identifier attribute or a fallback attribute for the experiment to run as expected.

Hi Madhu. I got the experiment working after sending the

user_uuid

as an attribute. Thank you.