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improve-ai/ios-sdk improve-5.0
AI Decisions, Ranking, Scoring & Multivariate Optimization for iOS
⭐️ 10
🕓 2 weeks ago
iOS
.package(url: "https://github.com/improve-ai/ios-sdk.git", from: "improve-5.0")

AI Decisions, Ranking, Scoring & Multivariate Optimization for iOS

Improve AI is a machine learning platform for quickly implementing app optimization, personalization, and recommendations for iOS, Android, and Python.

The SDKs provide simple APIs for AI decisions, ranking, scoring, and multivariate optimization that execute immediately, on-device, with zero network latency. Decisions and rewards are tracked in the cloud with the Improve AI Gym and updated models are trained regularly on AWS SageMaker.

Installation

In Xcode:

Initialization

import ImproveAI
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

    // track and model urls are obtained from your Improve AI Gym configuration
    trackUrl = 'https://xxxx.lambda-url.us-east-1.on.aws/'
    modelUrl = 'https://xxxx.s3.amazonaws.com/models/latest/greetings.mlmodel.gz'

    DecisionModel.defaultTrackURL = trackURL

    DecisionModel["greetings"].loadAsync(modelUrl)

    return true
}

Usage

The heart of Improve AI is the which() statement. which() is like an AI if/then statement.

greeting = DecisionModel["greetings"].which("Hello", "Howdy", "Hola")

which() takes a list of variants and returns the best - the "best" being the variant that provides the highest expected reward given the current conditions.

Decision models are easily trained with reinforcement learning:

if (likeTapped) {
    DecisionModel["greetings"].addReward(1.0)
}

With reinforcement learning, positive rewards are assigned for positive outcomes (a "carrot") and negative rewards are assigned for undesirable outcomes (a "stick").

which() automatically tracks it's decision with the Improve AI Gym. Rewards are credited to the most recent tracked decision for each model, including from a previous app session.

Contextual Decisions

Unlike A/B testing or feature flags, Improve AI uses context to make the best decision for each user. On iOS, the following context is automatically included:

  • $country - two letter country code
  • $lang - two letter language code
  • $tz - numeric GMT offset
  • $carrier - cellular network
  • $device - string portion of device model
  • $devicev - device version
  • $os - string portion of OS name
  • $osv - OS version
  • $pixels - screen width x screen height
  • $app - app name
  • $appv - app version
  • $sdkv - Improve AI SDK version
  • $weekday - (ISO 8601, monday==1.0, sunday==7.0) plus fractional part of day
  • $time - fractional day since midnight
  • $runtime - fractional days since session start
  • $day - fractional days since born
  • $d - the number of decisions for this model
  • $r - total rewards for this model
  • $r/d - total rewards/decisions
  • $d/day - decisions/$day

Using the context, on a Spanish speaker's device we expect our greetings model to learn to choose Hola.

Custom context can also be provided via given():

greeting = DecisionModel["greetings"].given(["language": "cowboy"])
                                     .which("Hello", "Howdy", "Hola")

Given the language is cowboy, the variant with the highest expected reward should be Howdy and the model would learn to make that choice.

Ranking

Ranking is a fundamental task in recommender systems, search engines, and social media feeds. Fast ranking can be performed on-device in a single line of code:

rankedWines = sommelierModel.given(entree).rank(wines)

Note: Decisions are not tracked when calling rank(). which() or decide() must be used to train models for ranking.

Scoring

Scoring makes it easy to turn any database table into a recommendation engine.

Simply add a score column to the database and update the score for each row.

scores = conversionRateModel.score(rows)

At query time, sort the query results descending by the score column and the first results will be the top recommendations. This works particularly well with local databases on mobile devices where the scores can be personalized to each individual user.

score() is also useful for crafting custom optimization algorithms or providing supplemental metrics in a multi-stage recommendation system.

Note: Decisions are not tracked when calling score(). which(), decide(), or optimize() must be used to train models for scoring.

Multivariate Optimization

Multivariate optimization is the joint optimization of multiple variables simultaneously. This is often useful for app configuration and performance tuning.

config = configModel.optimize({"bufferSize": [1024, 2048, 4096, 8192],
                               "videoBitrate": [256000, 384000, 512000]})

This example decides multiple variables simultaneously. Notice that instead of a single list of variants, a dictionary mapping keys to lists of variants is provided. This multi-variate mode jointly optimizes all variables for the highest expected reward.

optimize() automatically tracks it's decision with the Improve AI Gym. Rewards are credited to the most recent decision made by the model, including from a previous app session.

Variant Types

Variants and givens can be any object conforming to the Codable interface. This includes Int, Double, Bool, String, Dictionary, Array, nil, as well as any custom Codable objects. Object properties and nested items within collections are automatically encoded as machine learning features to assist in the decision making process.

The following are all valid:

greeting = greetingsModel.which("Hello", "Howdy", "Hola")

discount = discountModel.which(0.1, 0.2, 0.3)

enabled = featureFlagModel.which(true, false)

item = filterModel.which(item, nil)

themes = [[ "font": "Helvetica", "size": 12, "color": "#000000"  ],
          [ "font": "Comic Sans", "size": 16, "color": "#F0F0F0" ]]

theme = themeModel.which(themes)

To use a custom class or struct as a variant, declare it as implementing Codable:

struct Theme: Codable {
    var font: String
    var size: Int
    var color: String
}

theme = themeModel.which(themes)

Privacy

It is strongly recommended to never include Personally Identifiable Information (PII) in variants or givens so that it is never tracked, persisted, or used as training data.

Resources

Help Improve Our World

The mission of Improve AI is to make our corner of the world a little bit better each day. When each of us improve our corner of the world, the whole world becomes better. If your product or work does not make the world better, do not use Improve AI. Otherwise, welcome, I hope you find value in my labor of love.

-- Justin Chapweske

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