SDK and Frameworks in Mobile Development: What They Are, Types, and How to Choose

UI Frameworks for Mobile Development: UIKit, SwiftUI, Jetpack Compose

UI frameworks define the appearance and behavior of the user interface. UIKit is the main framework for iOS, in use since 2008 and supporting all iOS versions. SwiftUI is a more modern declarative framework introduced in 2019. Choosing a UI framework is the first decision when starting mobile development.

SwiftUI vs UIKit

SwiftUI uses a declarative approach: you describe how the interface should look, and the framework handles updates. SwiftUI reduces code for simple screens by 2–3 times compared to UIKit and automatically supports dark mode, Dynamic Type, and Accessibility.

UIKit is an imperative framework with finer control. UIKit remains the choice for complex custom interfaces and apps supporting iOS 12 and older. Many production apps use a hybrid approach: UIKit for complex screens, SwiftUI for new features.

Jetpack Compose is Google's declarative UI framework for Android, similar to SwiftUI. Compose uses Kotlin code instead of XML layouts, speeding up development and reducing bugs. It is compatible with existing View-based apps through AndroidView and ComposeView.

Jetpack is a set of Android libraries including Jetpack Compose, Navigation, Room, WorkManager and others. Jetpack solves common Android development tasks — from navigation to background work — through a unified API with backward compatibility.

Example of a simple screen in Jetpack Compose:

@Composable
fun Greeting(name: String) {
    Column(
        modifier = Modifier.padding(16.dp),
        horizontalAlignment = Alignment.CenterHorizontally
    ) {
        Text(
            text = "Hello, $name!",
            style = MaterialTheme.typography.h4
        )
        Button(onClick = { /* handle click */ }) {
            Text("Click me")
        }
    }
}

Cross-platform SDKs: Flutter, React Native, Xamarin

Cross-platform SDKs for mobile development allow writing one codebase for iOS and Android. Choosing a cross-platform SDK can save 30–50% of the development budget, but requires trade-offs in performance and access to native APIs.

Flutter vs React Native

Flutter from Google delivers better performance thanks to its custom Skia rendering engine. Flutter is ideal for projects with rich animations and custom design. React Native is better suited for teams with JavaScript experience and for apps with simple interfaces.

Kotlin Multiplatform Mobile (KMM) is an alternative approach where shared code is written in Kotlin, while UI is native. KMM allows sharing business logic, networking, and models between iOS and Android, preserving the native UX of each platform. It is IT Sectr's choice for enterprise projects.

Ionic and Apache Cordova use WebView for rendering. The WebView approach offers worse performance and UI but allows web developers to use JS/HTML/CSS. Suitable for simple wrapper apps over websites.

DI Frameworks: Dagger/Hilt, Koin, Swinject

Dependency Injection (DI) is a pattern where dependencies are passed to an object from the outside. In mobile development, DI frameworks automate the creation and injection of dependencies, making code more testable and maintainable.

Dagger/Hilt for Android

Dagger is the most popular DI framework for Android, using code generation. Dagger/Hilt is Google's official DI library for Android, built on top of Dagger. Hilt simplifies Dagger setup and automatically integrates with Jetpack components.

Koin is a DI framework for Kotlin without code generation. Koin is easier to set up but runs slower during initialization due to the lack of compile-time checks. Suitable for small projects where setup speed matters more than performance.

Example of setting up a module in Koin:

val appModule = module {
    single { ApiService() }
    factory { Repository(get()) }
    viewModel { MainViewModel(get()) }
}

fun main() {
    startKoin {
        modules(appModule)
    }
}

Swinject is a DI framework for Swift with a simple API. Swinject supports constructor injection, property injection, and method injection through a Service Container. It integrates with UIKit and SwiftUI via SwinjectStoryboard and SwinjectAutoregistration.

Choosing a DI framework depends on the platform and project size. For Android projects, IT Sectr recommends Hilt, for iOS — Swinject, for Kotlin Multiplatform — Koin due to minimal configuration overhead.

Networking Libraries: Retrofit, Alamofire, Ktor

Networking libraries for mobile development simplify working with HTTP requests and REST APIs. Retrofit (Android/Kotlin) is the most popular HTTP client for JVM with typed interfaces. It automatically serializes/deserializes JSON via OkHttp and converters (Gson, Moshi, Kotlinx Serialization).

Alamofire is the standard HTTP client for iOS/macOS in Swift. Alamofire provides a chained API, automatic session management, response validation, and error handling. A basic HTTP request in Alamofire looks like a one-liner.

Ktor Client is a multiplatform HTTP client from JetBrains. Ktor runs on JVM, iOS, macOS, Windows, Linux, and JavaScript with a unified API. Great for KMM projects where shared code must work on both platforms.

RxSwift and RxJava are libraries for reactive programming. Rx libraries are used for complex asynchronous operations — combining network requests, debounce, throttle, merging data streams. Combine is Apple's modern alternative for Swift.

Image Loading: Glide, Coil, Kingfisher

Image loading libraries in mobile development solve three tasks: async loading, caching, and display. Glide is the standard for Android, used in millions of apps. Supports GIF, video frames, animations, automatic memory and disk caching.

Coil (Coroutine Image Loader) is a modern alternative to Glide for Kotlin. Coil is 30% faster than Glide on first load and works with coroutines (suspend functions, Flow). Uses OkHttp for networking and supports SVG, GIF out of the box.

Kingfisher is the leading library for iOS by a single developer. Kingfisher supports caching, placeholders, progress indicators, error handling, and transition animations. SDWebImage is an older but still popular alternative with a large community.

Lottie is a library for rendering After Effects animations in real time. Lottie plays vector animations from JSON files without quality loss and with minimal file size. Supports color switching, speed, progress, and looping.

Game Engines: Unity, Unreal Engine

Specialized SDKs and engines are used for mobile game development. Unity is the most popular game engine for mobile platforms, powering over 50% of all mobile games. It uses C# and supports iOS, Android, WebGL, and desktop.

Unreal Engine focuses on photorealistic graphics. Unreal Engine 5 uses Nanite (virtual geometry) and Lumen (dynamic lighting), delivering console-quality visuals on mobile devices. Requires more powerful hardware and C++ experience.

SpriteKit and SceneKit are native 2D and 3D engines from Apple for iOS/macOS. SpriteKit is optimized for 2D games with minimal battery consumption and is ideal for casual games. SceneKit handles 3D scenes with physics, lighting, and animation.

Metal (Apple) and Vulkan (cross-platform) are low-level graphics APIs. Metal delivers maximum performance on Apple devices, Vulkan on Android and desktop (similar to DirectX 12 for Windows). OpenGL ES is outdated but still used for older devices.