iOS Glossary

iOS Basics

What is iOS?

Formerly known as iPhone OS, iOS is a mobile operating system for iPhone, iPad, and other mobile devices developed by Apple Inc. It is exclusively used only for Apple hardware.

As the second-most used mobile operating system, iOS is the basis for the development of three other operating systems: iPadOS, tvOS, and watchOS.

Ios Card
  • Developer: Apple Inc
  • First release: June 29, 2007
  • Latest version: iOS 15
  • Written in: C, C++, Swift, Objective-C, assembly language
  • Kernel type: Hybrid (XNU)
  • Source model: Closed, with open-source components
  • License: Property software except for open-source components
  • Website:
  • Users: 20 million registered developers
iOS Core
  • iOS SDK (iOS Software Development Kit)

    iOS SDK is a software development toolkit used for building mobile apps for Apple products including iPhone, iPad, and iPod touch. The development kit allows developers to access various functionalities and services of iOS to create and deliver innovative iOS apps.

    The iOS SDK is only available for macOS systems only. If you want to test your apps, get tech support, and distribute them through Apple’s App Store, you are required to subscribe to the Apple Developer Program.

    The iOS SDK is divided into separate sets of content:

    - Xcode

    Apple’s integrated development environment (IDE), Xcode provides powerful features that help developers build cutting-edge apps. Supporting source code for C, C++, Java, AppleScript, Objective-C, Objective-C++, Swift, Python, Ruby, and ResEdit, and many varieties of programming models, Xcode works perfectly with GitHub, Xcode Cloud, Bitbucket, and GitLab.

    - Swift

    Developed by Apple Inc. and the open-source community, Swift is an intuitive general-purpose, multi-paradigm, compiled programming language used for iOS, iPadOS, macOS, tvOS, and watchOS. Developed to replace Objective-C, this language has quickly become one of the fast-growing languages supporting the main core concepts of Objective-C, easy to write, and safe by design.

    - SwiftUI

    SwiftUI is a Swift cross-platform framework that helps you build user interfaces across Apple platforms.

    - TestFlight

    TestFlight is an online service used for testing mobile apps. Developers sign up for this service and can share their beta app with external or internal beta testers by inviting them via email or a link share.

iOS offers numerous frameworks to help developers create their apps. Below is a list of the most used ones.
  • App Clips

    App Clips allows users quick access to see what your app offers. It is a small, fast, and lightweight part of the app that is launched at the moment when needed. App Clips provide a complete user experience from start to finish of your app in only a few seconds. Once, the user is done experiencing your app, you can offer a full download from the App Store.

  • App Extensions

    App Extensions allow you to extend custom functionalities beyond your app which are available to users while there are using other apps.

    There are many types of extensions available in iOS. Some of them are:
    - Action
    - Audio Unit
    - Authentication Services
    - Account Authentication Modification
    - AutoFill Credential Provider
    - Broadcast Setup UI
    - Call Directory
    - ClassKit Content
    - Content Blocker
    - Custom Keyboard
    - File Provider
    - File Provider UI

  • Apple Pay

    Apple Pay offers an easy and secure way to complete payments by using Face ID, Touch ID, or double-clicking Apple Watch.

  • Health and Fitness (HealthKit)

    Developers can integrate HealthKit into their health and fitness apps to develop a more seamless user experience. Once a user gives permission for your app to read health and activity data, your app becomes an important data source that can deliver valuable information on health solutions.

  • HomeKit

    If you have an app that works to communicate and control connected accessories in users’ homes, you can use the HomeKit framework to configure accessories and action to control them.

  • IBeacon

    IBeacon provides countless opportunities for location awareness.

  • In-App Purchase

    In-App Purchase provides extra features and content directly in your app. It offers a consistent and safe experience, making it easy and seamless for users to manage their purchases and subscriptions. With in-app purchases, users can pay quickly in 45 currencies using nearly 200 payment methods, manage all subscriptions in one place, report a problem, see purchase history, and more.

    There are four types of in-app purchases:
    - Consumable
    - Non-consumable
    - Auto-renewable subscriptions
    - Non-renewable subscriptions

  • StoreKit

    This framework offers users a simple and secure way to purchase goods and services in your apps across all Apple platforms.

  • Localization

    With the Localization framework, you can make your app relevant only to those that need it, but you can also prepare your app to hit the global audience. The App Store is available in 175 regions and 40 languages.

  • Mac Catalyst

    Mac Catalyst allows you to share iOS code on your iPad apps.

  • Machine Learning

    This framework allows you to build intelligent features and enables new experiences for your apps.

  • Maps

    Maps and location information give your apps a sense of place with a custom annotation, highlighted regions, and overlays.

  • Nearby Interaction

    The Nearby Interaction framework allows you to easily integrate Ultra Wideband (UWB) in your apps and hardware accessories. You can build apps that interact with accessories easy as being in close proximity to an Apple device that has the U1 chip.

  • Notifications

    Notifications allow your users to be informed with relevant content no matter if your app is running in the background or is inactive.

  • SharePlay

    SharePlay gives you the opportunity to integrate your apps into FaceTime and the Group Activities API.

  • Sign in with Apple

    This framework makes it possible for users to sign in to your apps and website by using their Apple ID.

  • Siri

    SiriKit and Shortcuts will help your users to get things done with their voice, intelligent suggestions, or the Shortcuts app.

  • WidgetKit

    The WidgetKit framework along with widget API for SwiftUI helps you build widgets and makes them available across Apple platforms.

  • Other Frameworks

    The rest of the iOS Frameworks are:
    - 5G Networks
    - Accessories
    - Bonjour
    - CarPay
    - Developer ID
    - Education
    - iCloud and CloudKit
    - iMessage
    - Security
    - Wallet

Developer Tools
iOS developers have plenty of developer tool sets offered by Apple. Here are some of the most popular ones.
  • App Store Connect

    This suite of tools helps you easily upload, submit, and manage your apps on the App Store. It also provides you with sales reports, analytics, invites users to test your apps and more.

  • Core ML Model Deployment dashboard

    Your machine learning models can be safely built, developed, and delivered with the help of the Core ML Model Deployment dashboard.

  • Create ML

    Taking out the complexity of machine learning, Create ML helps you experience a new way of training machine learning models on your Mac.

  • Swift Playgrounds

    The revolutionary app for Mac and iPad, Swift Playgrounds helps you learn to develop and code apps using Swift.

  • Xcode Cloud

    Build into Xcode and specially designed for Apple developers, Xcode Cloud is a continuous integration and delivery service that help developers to accelerate the development and delivery of their apps.

  • Other Developer Tools

    The rest of the developer tools include:
    - CloudKit Console
    - Command Line Tools
    - Feedback Assistant
    - MapKit JS Dashboard
    - Reality Composer
    - Reality Converter
    - SF Symbols
    - Transporter

  • Graphic and Games

    iOS provides numerous possibilities for game developers. Apple Arcade is a game subscription platform that provides customers unlimited access to over 200 premium games, new releases, award winners, and more.

    Some of the resources for building games include:

    Metal offers a low-overhead API for developing 3D pro applications and games providing a rich shading language with strong integration between graphics and computer programs.

    A high-level 3D graphic framework, SceneKit helps developers build 3D animated scenes and effects in their apps.

    High-performance and battery-efficient 2D games can be easily created with the help of SpriteKit.

    Augmented Reality
    AR platform helps you develop unparalleled augmented reality experiences. The powerful frameworks such as ARKit and RealityKit along with numerous dev tools allow you to build interesting ideas in AR.

    Media and Web

    iOS also provides numerous tools and resources to help build media and web apps such as:
    - AirPlay
    - AirPrint
    - Apple News Format
    - Audio
    - AVFoundation
    - HTTP Live Streaming (HLS)
    - Live Photos
    - MusicKit
    - Safari & Safari Extensions
    - ShazamKit
    - WebKit