SwiftUI
Apple's declarative UI framework. Launched WWDC 2019. Replacement for UIKit (iOS) + AppKit (Mac). Inspired by React/Flutter: state → view, automatic re-render.
@State, @Binding, @ObservedObject, @Environment propagate data. Requires iOS 13+/macOS 10.15+. Early versions (1.0–2.0) had bugs + missing features → many teams stuck with UIKit. Stabilized around iOS 16+ (2022). Strong in Apple-only contexts (visionOS apps are SwiftUI-first). Cross-platform pitch (Mac + iOS + watchOS + tvOS + visionOS same code) is the killer feature within the Apple ecosystem.