Call an iOS API

battery.lucent.ts

import { PLATFORM } from "lucent:platform";
import { UIDevice, UIDevice_BatteryState } from "lucent:ios/UIKit";
import { main } from "lucent:thread";
import { error } from "lucent:core";

export async function isCharging(): Promise<boolean> {
  if (PLATFORM === "ios") {
    return main(() => {
      UIDevice.current.isBatteryMonitoringEnabled = true;
      const state = UIDevice.current.batteryState;
      return state === UIDevice_BatteryState.charging || state === UIDevice_BatteryState.full;
    });
  } else {
    throw error("E_UNSUPPORTED", "Only iOS is implemented");
  }
}

See the C++

iOS

m_battery.mm

// Generated by Lucent from battery.lucent.ts. Do not edit.
#import <UIKit/UIKit.h>
#include <lucent/platform/ios.h>
#include "m_battery.h"

#pragma push_macro("isCharging")
#undef isCharging
#pragma push_macro("state")
#undef state

static_assert(UIDeviceBatteryStateCharging == 2, "UIDevice_BatteryState.charging in the UIKit binding schema");
static_assert(UIDeviceBatteryStateFull == 3, "UIDevice_BatteryState.full in the UIKit binding schema");

namespace lucent_app {

lucent::Promise<bool> m_battery::isCharging() {
#line 7 "battery.lucent.ts"
  {
#line 8 "battery.lucent.ts"
    lucent::Fn<bool()> v0_ = lucent::Fn<bool()>([]() mutable -> bool {
#line 9 "battery.lucent.ts"
      lucent::NativeRef v0_ = lucent::objc::wrap([UIDevice currentDevice], "UIDevice.current");
      (void)({ auto v_ = true; [((UIDevice*)lucent::objc::unwrap(v0_)) setBatteryMonitoringEnabled:v_ ? YES : NO]; v_; });
#line 10 "battery.lucent.ts"
      lucent::NativeRef v3_ = lucent::objc::wrap([UIDevice currentDevice], "UIDevice.current");
      double state = static_cast<double>([((UIDevice*)lucent::objc::unwrap(v3_)) batteryState]);
#line 11 "battery.lucent.ts"
      double v6_ = 2.0;
      bool v7_ = state == v6_;
      bool v11_{};
      if (v7_) {
        v11_ = v7_;
      } else {
        double v9_ = 3.0;
        v11_ = state == v9_;
      }
#line 11 "battery.lucent.ts"
      return v11_;
    });
#line 8 "battery.lucent.ts"
    lucent::Promise<bool> v1_ = lucent::runOnMain(v0_);
    bool v2_ = co_await v1_;
    co_return v2_;
  }
}

void m_battery::init() {
}

}  // namespace lucent_app

#pragma pop_macro("state")
#pragma pop_macro("isCharging")

Android

m_battery.cpp

// Generated by Lucent from battery.lucent.ts. Do not edit.
#include "m_battery.h"

#pragma push_macro("isCharging")
#undef isCharging

namespace lucent_app {

lucent::Promise<bool> m_battery::isCharging() {
#line 7 "battery.lucent.ts"
  {
#line 14 "battery.lucent.ts"
    lucent::Error v2_ = lucent::withSite(lucent::errorWithCode(LUCENT_STR("E_UNSUPPORTED"), LUCENT_STR("Only iOS is implemented")), __FILE__, __LINE__, "isCharging");
    lucent::throwError(v2_);
  }
  co_return []() -> bool {
    lucent::unreachable();
  }();
}

void m_battery::init() {
}

}  // namespace lucent_app

#pragma pop_macro("isCharging")

• Import from lucent:ios/<Framework>: any framework of your Xcode's SDK, or of the app's pods.
• Names are Swift's. A nested type joins its parts with _: Swift's UIDevice.BatteryState is UIDevice_BatteryState.
• UIKit is main-thread only, so the calls sit inside main(). Anywhere else they fail to compile with LUCENT3006.
• Return plain values: SDK objects can't cross to JavaScript.

A method with a completion handler is also a promise, under the name Swift gives its async form. An NSError becomes a thrown error. SDK types has every rule.

Caution

The first import of a large framework reads it from Xcode, which takes up to a minute once. lucent sdk prefetch does it ahead of time.