A lightweight A/B Testing and Feature Flag Swift library focused on performance ⚡️

Usage

Example

To run the example project, clone the repo, and run pod install from the Example directory first.

Installation

Tesfy is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'Tesfy'

Initialization

Import and instantiate it with a datafile. A datafile is a json that defines the experiments and features avaliable. Ideally this file should be hosted somewhere outside your application (for example in S3), so it could be fetched during boostrap or every certain time. This will allow you to make changes to the file without deploying the application.

import Tesfy

let datafile = """
    {
        "experiments": {
            "experiment-1": {
                "id": "experiment-1",
                "percentage": 90,
                "variations": [{
                    "id": "0",
                    "percentage": 50
                }, {
                    "id": "1",
                    "percentage": 50
                }]
            },
            "experiment-2": {
                "id": "experiment-2",
                "percentage": 100,
                "variations": [{
                    "id": "0",
                    "percentage": 100
                }],
                "audience": {
                    "==": [{ "var": "countryCode" }, "us"]
                }
            }
        },
        "features": {
            "feature-1": {
                "id": "feature-1",
                "percentage": 50
            }
        }
    }
"""

let tesfy = Tesfy(datafile: datafile)

Experiments

Check which variation of an experiment is assigned to a user.

let userId = "676380e0-7793-44d6-9189-eb5868e17a86"
let experimentId = "experiment-1"

tesfy.getVariationId(experimentId: experimentId, userId: userId) // "1"

Feature Flags

Check if a feature is enabled for a user.

let userId = "676380e0-7793-44d6-9189-eb5868e17a86"
let featureId = "feature-1"

tesfy.isFeatureEnabled(featureId: featureId, userId: userId) // true

Audiences

Use attributes to target an specific audience by using JsonLogic.

let userId = "676380e0-7793-44d6-9189-eb5868e17a86"
let experimentId = "experiment-2"

tesfy.getVariationId(experimentId: experimentId, userId: userId, attributes: "{ \"countryCode\": \"ve\" }") // nil
tesfy.getVariationId(experimentId: experimentId, userId: userId, attributes: "{ \"countryCode\": \"us\" }") // "0"

Sticky Bucketing

Optionally add a storage layer when instantiating tesfy by conforming to the protocol TesfyStorable. This layer could be whatever you want (UserDefaults, Keychain, Core Data, SQLite, etc.). This way even allocation or attributes changes in users will stick with the same variation.

class TesfyStorage: TesfyStorable {
    var storage: [String: String]
    
    init(storage: [String: String]? = [:]) {
        self.storage = storage ?? [:]
    }
    
    func get(id: String) -> String? {
        return storage[id]
    }
    
    func store(id: String, value: String?) {
        self.storage[id] = value
    }
}

let tesfyStorage = TesfyStorage()
let tesfy = Tesfy(datafile: datafile, storage: tesfyStorage)

let userId = "676380e0-7793-44d6-9189-eb5868e17a86"
let experimentId = "experiment-2"

tesfy.getVariationId(experimentId: experimentId, userId: userId, attributes: "{ \"countryCode\": \"us\" }") // "0"
tesfy.getVariationId(experimentId: experimentId, userId: userId, attributes: "{ \"countryCode\": \"ve\" }") // "0"

Integrations

Tesfy is also available in different languages for Android or JavaScript (vanilla and React):

• Tesfy Kotlin
• Tesfy JavaScript
• Tesfy React

Feedback

Pull requests, feature ideas and bug reports are very welcome. We highly appreciate any feedback.

Author

Pedro Valdivieso (gringox)

License

Tesfy is available under the MIT license. See the LICENSE file for more info.