Swift / SwiftUI

Swift gives you direct access to every Apple framework with SwiftUI for declarative components.

Setup

No additional setup is required. Xcode provides swiftc for compilation, which is already available if you have a working React Native iOS development environment.

SwiftUI components

Mark a SwiftUI View with // @nativ_component:

SwiftCounter.swift

import SwiftUI

// @nativ_component
struct SwiftCounterView: View {
    let title: String
    let color: Color

    var body: some View {
        VStack(spacing: 8) {
            Text(title)
                .font(.system(size: 18, weight: .bold))
                .foregroundColor(.white)
            Text("SwiftUI inside React Native")
                .font(.system(size: 12))
                .foregroundColor(.white.opacity(0.7))
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(color)
    }
}

App.tsx

import SwiftCounter from './SwiftCounter';

<SwiftCounter
  title="Hello from SwiftUI!"
  r={0.9}
  g={0.5}
  b={0.9}
  style={{ width: '100%', height: 80, borderRadius: 12, overflow: 'hidden' }}
/>

Functions

Use // @nativ_export to export plain Swift functions:

platform_info.swift

import Foundation
import UIKit

// @nativ_export
func deviceName() -> String {
    return UIDevice.current.name
}

// @nativ_export
func systemVersion() -> String {
    return "iOS " + UIDevice.current.systemVersion
}

// @nativ_export
func batteryLevel() -> Float {
    UIDevice.current.isBatteryMonitoringEnabled = true
    return UIDevice.current.batteryLevel
}

App.tsx

import { deviceName, systemVersion, batteryLevel } from './platform_info';

<Text>device: {deviceName()}</Text>
<Text>os: {systemVersion()}</Text>
<Text>battery: {String(batteryLevel())}</Text>

Async functions

Use // @nativ_export(async) for functions that do heavy work:

async_utils.swift

import Foundation

// @nativ_export(async)
func slowHello(name: String) -> String {
    Thread.sleep(forTimeInterval: 1.0)
    return "Hello \(name) from Swift (after 1s)!"
}

App.tsx

import { slowHello } from './async_utils';

const result = await slowHello('World');

Main thread dispatch

UIKit APIs must be called from the main thread. Add main to the annotation:

// @nativ_export(sync, main)
func screenBrightness() -> Float {
    return Float(UIScreen.main.brightness)
}

The bridge wraps the call in DispatchQueue.main.sync { } automatically. Use this for any function that touches UIKit, haptics, or other UI APIs.

Using Apple frameworks

Any iOS framework is available — CoreLocation, AVFoundation, CoreML, ARKit, HealthKit, and more:

import CoreLocation

// @nativ_export
func isLocationEnabled() -> Bool {
    return CLLocationManager.locationServicesEnabled()
}

import AVFoundation

// @nativ_export
func audioCategory() -> String {
    return AVAudioSession.sharedInstance().category.rawValue
}

Hot-reload

Swift hot-reload uses dlopen on code-signed .dylib files:

Edit your .swift file
Save
Metro compiles it with swiftc
The .dylib is code-signed automatically
The device loads it via dlopen
The component re-renders

No Xcode rebuild needed.

Swift / SwiftUI

Setup

SwiftUI components

Functions

Async functions

Main thread dispatch

Using Apple frameworks

Hot-reload

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