nsh/android

nsh/android holds APIs that only Android has. The module can be imported on every platform, so one bundle runs everywhere: elsewhere its functions do nothing, and isAvailable tells you whether you are on Android.

import { BackHandler, isAvailable, setStatusBarBackgroundColor, Toast } from "nsh/android";

Android-only props of elements and components are not here: they go in the android={{…}} prop (for example <View android={{ elevation: 4, ripple: … }} />). See Platform-specific code.

#isAvailable

const isAvailable: boolean;

true on Android; false elsewhere.

#Toast

const Toast: {
  show(message: string, duration?: "short" | "long" | null): void;
};

Shows a short message at the bottom of the screen (Android’s toast). duration is "short" by default.

import { Platform } from "nsh/device";
import { Toast } from "nsh/android";
import { Alert } from "nsh/ui/mobile";

const notify = (message: string) =>
  Platform.OS === "android" ? Toast.show(message) : Alert.alert("Done", message);

#BackHandler

const BackHandler: {
  addEventListener(event: "hardwareBackPress", listener: () => boolean | void): { remove(): void };
  exitApp(): void;
};

The system back button and back gesture. Modals and navigation stacks handle the back press first (a modal closes, a stack pops); only when none of them takes it do BackHandler’s listeners run.

Member	Description
addEventListener("hardwareBackPress", listener)	listener returns true when it handled the press. The most recently added listener runs first. If no listener handles it, the app exits. Returns a subscription to remove().
exitApp()	Leaves the app.

import { cleanup, signal } from "nsh";
import { BackHandler } from "nsh/android";
import { Alert } from "nsh/ui/mobile";

function Editor() {
  const dirty = signal(false);
  const sub = BackHandler.addEventListener("hardwareBackPress", () => {
    if (!dirty()) return false; // let the app go back or exit
    Alert.alert("Discard changes?", undefined, [{ text: "Keep" }, { text: "Discard", style: "destructive" }]).then(
      (i) => i === 1 && BackHandler.exitApp(),
    );
    return true;
  });
  cleanup(() => sub.remove());
  // ...
}

#setStatusBarBackgroundColor

function setStatusBarBackgroundColor(backgroundColor: string, animated?: boolean | null): void;

Sets the status bar’s color, below what rendered <StatusBar android={{ backgroundColor }}> components set (the last mounted StatusBar wins over this base value). It has an effect on Android versions before edge-to-edge became mandatory (API 35); from API 35 the status bar is transparent and your content draws behind it.

setStatusBarBackgroundColor("#1e293b", true);

See StatusBar for the component.