Run code on the main thread

screen.lucent.ts

import { PLATFORM } from "lucent:platform";
import { UIApplication } from "lucent:ios/UIKit";
import { main } from "lucent:thread";

export async function keepAwake(on: boolean): Promise<void> {
  if (PLATFORM === "ios") {
    await main(() => {
      UIApplication.shared.isIdleTimerDisabled = on;
    });
  }
}

main(f) from lucent:thread runs f on the main thread and resolves with its result. The caller doesn't block, so call it from async code.

• On iOS, APIs that Swift marks @MainActor, such as UIKit's, compile only inside main() (LUCENT3006). So do SDK callbacks the SDK calls on the main thread.
• f must be a function literal, and it can't be async. Keep it short: move data in and out, and do the work around it.
• Android has no such check. Some Android APIs still need the main thread, such as the clipboard; call them inside main() too.
• Objects that deliver to the thread that made them, such as CLLocationManager, should be made inside main().