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Tauri

Mobile Plugin Development

Plugins can run native mobile code written in Kotlin (or Java) and Swift. The default plugin template includes an Android library project using Kotlin and a Swift package including an example mobile command showing how to trigger its execution from Rust code.

Follow the steps in the Plugin Development guide to initialize a new plugin project.

If you have an existing plugin and would like to add Android or iOS capabilities to it, you can use plugin android init and plugin ios init to bootstrap the mobile library projects and guide you through the changes needed.

The default plugin template splits the plugin’s implementation into two separate modules: desktop.rs and mobile.rs.

The desktop implementation uses Rust code to implement a functionality, while the mobile implementation sends a message to the native mobile code to execute a function and get a result back. If shared logic is needed across both implementations, it can be defined in lib.rs:

lib.rs
use tauri::Runtime;
impl<R: Runtime> <plugin-name><R> {
pub fn do_something(&self) {
// do something that is a shared implementation between desktop and mobile
}
}

This implementation simplifies the process of sharing an API that can be used both by commands and Rust code.

A Tauri plugin for Android is defined as a Kotlin class that extends app.tauri.plugin.Plugin and is annoted with app.tauri.annotation.TauriPlugin. Each method annotated with app.tauri.annotation.Command can be called by Rust or JavaScript.

Tauri uses Kotlin by default for the Android plugin implementation, but you can switch to Java if you prefer. After generating a plugin, right click the Kotlin plugin class in Android Studio and select the “Convert Kotlin file to Java file” option from the menu. Android Studio will guide you through the project migration to Java.

A Tauri plugin for iOS is defined as a Swift class that extends the Plugin class from the Tauri package. Each function with the @objc attribute and the (_ invoke: Invoke) parameter (for example @objc private func download(_ invoke: Invoke) { }) can be called by Rust or JavaScript.

The plugin is defined as a Swift package so that you can use its package manager to manage dependencies.

Refer to the Plugin Configuration section of the Plugin Development guide for more details on developing plugin configurations.

The plugin instance on mobile has a getter for the plugin configuration:

@TauriPlugin
class ExamplePlugin(private val activity: Activity): Plugin(activity) {
override fun load(webView: WebView) {
val timeout = this.config.getInt("timeout", 30)
}
}

Plugins can hook into several lifecycle events:

  • load: When the plugin is loaded into the web view
  • onNewIntent: Android only, when the activity is re-launched

There are also the additional lifecycle events for plugins in the Plugin Development guide.

  • When: When the plugin is loaded into the web view
  • Why: Execute plugin initialization code
@TauriPlugin
class ExamplePlugin(private val activity: Activity): Plugin(activity) {
override fun load(webView: WebView) {
// perform plugin setup here
}
}

Note: This is only available on Android.

  • When: When the activity is re-launched. See Activity#onNewIntent for more information.
  • Why: Handle application re-launch such as when a notification is clicked or a deep link is accessed.
// import android.content.Intent
@TauriPlugin
class ExamplePlugin(private val activity: Activity): Plugin(activity) {
override fun onNewIntent(intent: Intent) {
// handle new intent event
}
}

There is a plugin class inside the respective mobile projects where commands can be defined that can be called by the Rust code:

@TauriPlugin
class ExamplePlugin(private val activity: Activity): Plugin(activity) {
@Command
fun openCamera(invoke: Invoke) {
val allowEdit = invoke.getBoolean("allowEdit", false)
val quality = invoke.getInt("quality", 100)
val ret = JSObject()
ret.put("path", "/path/to/photo.jpg")
invoke.resolve(ret)
}
}

Use the tauri::plugin::PluginHandle to call a mobile command from Rust:

use std::path::PathBuf;
use serde::{Deserialize, Serialize};
use tauri::Runtime;
#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
pub struct CameraRequest {
quality: usize,
allow_edit: bool,
}
#[derive(Deserialize)]
pub struct Photo {
path: PathBuf,
}
impl<R: Runtime> <plugin-name;pascal-case><R> {
pub fn open_camera(&self, payload: CameraRequest) -> crate::Result<Photo> {
self
.0
.run_mobile_plugin("openCamera", payload)
.map_err(Into::into)
}
}

If a plugin requires permissions from the end user, Tauri simplifies the process of checking and requesting permissions.

First define the list of permissions needed and an alias to identify each group in code. This is done inside the TauriPlugin annotation:

@TauriPlugin(
permissions = [
Permission(strings = [Manifest.permission.POST_NOTIFICATIONS], alias = "postNotification")
]
)
class ExamplePlugin(private val activity: Activity): Plugin(activity) { }

Tauri automatically implements two commands for the plugin: checkPermissions and requestPermissions. Those commands can be directly called from JavaScript or Rust:

import { invoke } from '@tauri-apps/api/tauri'
type PermissionState = 'granted' | 'denied' | 'prompt' | 'prompt-with-rationale'
interface Permissions {
postNotification: PermissionState
}
// check permission state
const permission = await invoke<Permissions>('plugin:<plugin-name>|checkPermissions')
if (permission.postNotification === 'prompt-with-rationale') {
// show information to the user about why permission is needed
}
// request permission
if (permission.postNotification.startsWith('prompt')) {
const state = await invoke<Permissions>('plugin:<plugin-name>|requestPermissions', { permissions: ['postNotification'] })
}

Plugins can emit events at any point of time using the trigger function:

@TauriPlugin
class ExamplePlugin(private val activity: Activity): Plugin(activity) {
override fun load(webView: WebView) {
trigger("load", JSObject())
}
override fun onNewIntent(intent: Intent) {
// handle new intent event
if (intent.action == Intent.ACTION_VIEW) {
val data = intent.data.toString()
val event = JSObject()
event.put("data", data)
trigger("newIntent", event)
}
}
@Command
fun openCamera(invoke: Invoke) {
val payload = JSObject()
payload.put("open", true)
trigger("camera", payload)
}
}

The helper functionss can then be called from the NPM package by using the addPluginListener helper function:

import { addPluginListener, PluginListener } from '@tauri-apps/api/tauri';
export async function onRequest(
handler: (url: string) => void
): Promise<PluginListener> {
return await addPluginListener(
'<plugin-name>',
'event-name',
handler
);
}

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