Device Capabilities

All device APIs in Mob follow a consistent pattern: call the function from a callback (returning the socket unchanged), then handle the result in handle_info/2. APIs never block the screen process.

Permissions

Some capabilities require an OS permission before they can be used. Request permissions via Mob.Permissions.request/2. The result arrives asynchronously:

def mount(_params, _session, socket) do
  socket = Mob.Permissions.request(socket, :camera)
  {:ok, socket}
end

def handle_info({:permission, :camera, :granted}, socket) do
  {:noreply, Mob.Socket.assign(socket, :camera_ready, true)}
end

def handle_info({:permission, :camera, :denied}, socket) do
  {:noreply, Mob.Socket.assign(socket, :camera_ready, false)}
end

Capabilities that require permission: :camera, :microphone, :photo_library, :location, :notifications

No permission needed: haptics, clipboard, share sheet, file picker.

Haptic feedback

Mob.Haptic.trigger/2 fires synchronously (no handle_info needed) and returns the socket:

def handle_event("tap", %{"tag" => "purchase"}, socket) do
  socket = Mob.Haptic.trigger(socket, :success)
  {:noreply, socket}
end

Feedback types: :light, :medium, :heavy, :success, :error, :warning

iOS uses UIImpactFeedbackGenerator / UINotificationFeedbackGenerator. Android uses View.performHapticFeedback.

Clipboard

# Write to clipboard
def handle_event("tap", %{"tag" => "copy"}, socket) do
  socket = Mob.Clipboard.write(socket, socket.assigns.code)
  {:noreply, socket}
end

# Read from clipboard — result arrives in handle_info
def handle_event("tap", %{"tag" => "paste"}, socket) do
  socket = Mob.Clipboard.read(socket)
  {:noreply, socket}
end

def handle_info({:clipboard, :read, text}, socket) do
  {:noreply, Mob.Socket.assign(socket, :pasted_text, text)}
end

Opens the platform's native share sheet (iOS: UIActivityViewController, Android: ACTION_SEND):

def handle_event("tap", %{"tag" => "share"}, socket) do
  socket = Mob.Share.sheet(socket, text: "Check out this app!", url: "https://example.com")
  {:noreply, socket}
end

Options: :text, :url, :title

Camera

Requires :camera permission (and :microphone for video).

# Capture a photo
socket = Mob.Camera.capture_photo(socket)
socket = Mob.Camera.capture_photo(socket, quality: :medium)

# Record a video
socket = Mob.Camera.capture_video(socket)
socket = Mob.Camera.capture_video(socket, max_duration: 30)

# Results:
def handle_info({:camera, :photo, %{path: path, width: w, height: h}}, socket) do
  {:noreply, Mob.Socket.assign(socket, :photo_path, path)}
end

def handle_info({:camera, :video, %{path: path, duration: seconds}}, socket) do
  {:noreply, Mob.Socket.assign(socket, :video_path, path)}
end

def handle_info({:camera, :cancelled}, socket) do
  {:noreply, socket}
end

path is a local temp file. Copy it to a permanent location before the next capture.

Photos

Browse and pick from the photo library. Requires :photo_library permission.

socket = Mob.Photos.pick(socket)
socket = Mob.Photos.pick(socket, max: 5)  # pick up to 5

def handle_info({:photos, :picked, photos}, socket) do
  # photos is a list of %{path: path, width: w, height: h} maps
  {:noreply, Mob.Socket.assign(socket, :photos, photos)}
end

def handle_info({:photos, :cancelled}, socket) do
  {:noreply, socket}
end

Files

Open the system file picker:

socket = Mob.Files.pick(socket)
socket = Mob.Files.pick(socket, types: ["public.pdf", "public.text"])  # iOS UTI strings
socket = Mob.Files.pick(socket, types: ["application/pdf", "text/plain"])  # Android MIME types

def handle_info({:files, :picked, files}, socket) do
  # files is a list of %{path: path, name: name, size: bytes} maps
  {:noreply, Mob.Socket.assign(socket, :files, files)}
end

Platform note: types uses iOS UTI strings on iOS ("public.pdf") and MIME type strings on Android ("application/pdf"). To support both platforms with the same call, pass both forms — the platform ignores strings it doesn't recognise. See Platform-specific props for a cleaner pattern.


## Camera preview

Display a live camera feed inline (no OS permission dialog for preview):

def mount(_params, _session, socket) do socket = Mob.Camera.start_preview(socket, facing: :back)

end

def render(assigns) do ~MOB""" <Column>

<CameraPreview facing={:back} weight={1} />
<Button text="Flip" on_tap={{self(), :flip}} />

""" end

def terminate(_reason, socket) do Mob.Camera.stop_preview(socket) :ok end


The `:camera_preview` component requires an active preview session — call `start_preview/2` before mounting and `stop_preview/1` in `terminate/2`.

## Audio recording

Requires `:microphone` permission.

socket = Mob.Audio.start_recording(socket) socket = Mob.Audio.start_recording(socket, format: :aac, quality: :medium) socket = Mob.Audio.stop_recording(socket)

def handle_info({:audio, :recorded, %{path: path, duration: seconds}}, socket) do

end

def handle_info({:audio, :error, reason}, socket) do

end


Recording formats: `:aac` (default), `:wav`. Quality: `:low`, `:medium` (default), `:high`.

## Audio playback

No permission needed. Plays local files or remote URLs.

socket = Mob.Audio.play(socket, "/path/to/clip.m4a") socket = Mob.Audio.play(socket, path, loop: true, volume: 0.8) socket = Mob.Audio.stop_playback(socket) socket = Mob.Audio.set_volume(socket, 0.5) # adjust without stopping

def handle_info({:audio, :playback_finished, %{path: path}}, socket) do

end

def handle_info({:audio, :playback_error, %{reason: reason}}, socket) do

end


iOS uses `AVAudioPlayer` / `AVPlayer`. Android uses `MediaPlayer`.

## Location

Requires `:location` permission.

Single fix

socket = Mob.Location.get_once(socket)

Continuous updates

socket = Mob.Location.start(socket) socket = Mob.Location.start(socket, accuracy: :high) # :high | :balanced | :low socket = Mob.Location.stop(socket)

def handle_info({:location, %{lat: lat, lon: lon, accuracy: acc, altitude: alt}}, socket) do {:noreply, Mob.Socket.assign(socket, :location, %{lat: lat, lon: lon})} end

def handle_info({:location, :error, reason}, socket) do

end


iOS uses `CLLocationManager`. Android uses `FusedLocationProviderClient`.

## Motion (accelerometer / gyroscope)

socket = Mob.Motion.start(socket) socket = Mob.Motion.start(socket, interval_ms: 100) socket = Mob.Motion.stop(socket)

def handle_info({:motion, %{ax: ax, ay: ay, az: az, gx: gx, gy: gy, gz: gz}}, socket) do {:noreply, Mob.Socket.assign(socket, :motion, %{ax: ax, ay: ay, az: az})} end


## Biometric authentication

socket = Mob.Biometric.authenticate(socket, reason: "Confirm your identity")

def handle_info({:biometric, :success}, socket) do

end

def handle_info({:biometric, :failure, reason}, socket) do

end


iOS uses Face ID / Touch ID. Android uses `BiometricPrompt`.

## QR / barcode scanner

socket = Mob.Scanner.scan(socket)

def handle_info({:scan, :result, %{type: type, value: value}}, socket) do # type: :qr | :ean | :upc | etc.

end

def handle_info({:scan, :cancelled}, socket) do

end


## Notifications

See also [Mob.Notify](Mob.Notify.html) for the full API.

Requires `:notifications` permission.

### Local notifications

Schedule

Mob.Notify.schedule(socket, id: "reminder_1", title: "Time to check in", body: "Open the app to see today's updates", at: ~U[2026-04-16 09:00:00Z], # or delay_seconds: 60 data: %{screen: "reminders"} )

Cancel

Mob.Notify.cancel(socket, "reminder_1")

Receive in handle_info (all app states: foreground, background, relaunched):

def handle_info({:notification, %{id: id, data: data, source: :local}}, socket) do

end


### Push notifications

See the [Push Notifications guide](push_notifications.md) for the full walkthrough — server setup, credential configuration, token handling, delivery lifecycle, and appearance options.

Quick reference:

After :notifications permission is granted:

Receive the device token — store it server-side with the platform:

def handle_info({:push_token, platform, token}, socket) do MyApp.PushTokens.upsert(socket.assigns.user_id, token, platform)

end

Receive push notifications (foreground, background tap, or killed → tapped):

def handle_info({:notification, notif}, socket) do # notif["source"] == "push", notif["data"] contains your custom payload

end


To send from your server, add [`mob_push`](https://hexdocs.pm/mob_push) to your server dependencies.

## Storage

App-local file storage using named locations instead of raw paths. No permission needed.

Resolve a location to its absolute path

path = Mob.Storage.dir(:documents) # persists, user-visible on iOS path = Mob.Storage.dir(:cache) # persists until OS needs space path = Mob.Storage.dir(:temp) # ephemeral, may be purged any time path = Mob.Storage.dir(:app_support) # persists, hidden from user, backed up on iOS

File operations

= Mob.Storage.list(:documents) # returns full paths {:ok, meta} = Mob.Storage.stat("/path/to/file") # %{name, path, size, modified_at} {:ok, path} = Mob.Storage.write("/path/file.txt", "contents") {:ok, data} = Mob.Storage.read("/path/file.txt") {:ok, dest} = Mob.Storage.copy("/path/src.txt", :documents) # keeps basename {:ok, dest} = Mob.Storage.move("/path/src.txt", "/path/dest.txt") :ok = Mob.Storage.delete("/path/file.txt")

ext = Mob.Storage.extension("/tmp/clip.mp4") # => ".mp4"


All operations that can fail return `{:ok, value} | {:error, posix}`. `dir/1` raises on an unknown location atom.

For saving to the native media library (Camera Roll, Downloads), see `Mob.Storage.Apple` and `Mob.Storage.Android`.

## WebView

Embed a native web view and communicate with it over a JS bridge. No permission needed.

def render(assigns) do ~MOB""" <WebView url="https://example.com" allow={["https://example.com"]} show_url={true} weight={1} /> """ end

Send a message to Elixir from JS:

window.mob.send({ event: "clicked", id: 42 })

def handle_info({:webview, :message, %{"event" => "clicked", "id" => id}}, socket) do

end

A navigation attempt was blocked by the allow: whitelist

def handle_info({:webview, :blocked, url}, socket) do

end


Push a message from Elixir into the page (calls `window.mob.onMessage` handlers):

socket = Mob.WebView.post_message(socket, %{type: "update", value: 42})


Evaluate arbitrary JavaScript and receive the result:

socket = Mob.WebView.eval_js(socket, "document.title")

Result arrives as:

def handle_info({:webview, :eval_result, result}, socket) do

end


Props: `:url` (required), `:allow` (list of URL prefixes — blocks others), `:show_url` (native URL bar), `:title` (static label overriding `:show_url`), `:width`, `:height`.

> **Platform note:** WebView is supported on both iOS and Android.

## Alerts and toasts

`Mob.Alert` shows native dialogs and status messages. No permission needed.

### Alert dialog

Centered modal for confirmations and errors (iOS: `UIAlertController(.alert)`, Android: `AlertDialog`).

def handle_info({:tap, :delete}, socket) do Mob.Alert.alert(socket,

title:   "Delete item?",
message: "This cannot be undone.",
buttons: [
  [label: "Delete", style: :destructive, action: :confirmed_delete],
  [label: "Cancel", style: :cancel]
]

)

end

def handle_info({:alert, :confirmed_delete}, socket) do

end

def handle_info({:alert, :dismiss}, socket) do

end


Dismissing without tapping a button (e.g. Android back gesture) sends `{:alert, :dismiss}`.

### Action sheet

Bottom-anchored list for choosing between actions (iOS: `UIAlertController(.actionSheet)`, Android: list dialog).

Mob.Alert.action_sheet(socket, title: "Share photo", buttons: [

[label: "Save to Photos", action: :save],
[label: "Copy link",      action: :copy],
[label: "Cancel",         style: :cancel]

] )

def handle_info({:alert, :save}, socket), do: {:noreply, save_photo(socket)} def handle_info({:alert, :copy}, socket), do: {:noreply, copy_link(socket)} def handle_info({:alert, :dismiss}, socket), do: {:noreply, socket}


### Toast

Ephemeral status message with no callback.

Mob.Alert.toast(socket, "Saved!") Mob.Alert.toast(socket, "File uploaded", duration: :long)


Duration: `:short` (default, ~2 s) or `:long` (~4 s). iOS renders a floating label overlay; Android uses `Toast`.

### Button options

| Key | Values | Default |
|-----|--------|---------|
| `:label` | string | `""` |
| `:style` | `:default`, `:cancel`, `:destructive` | `:default` |
| `:action` | atom — delivered as `{:alert, atom}` to `handle_info/2` | `:dismiss` |

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