Dala.Hardware.NFC (dala v0.3.0)

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NFC (Near Field Communication) tag reading.

Reads NDEF tags via the device's NFC reader. Requires the app to have NFC entitlement (iOS) or android.permission.NFC (Android).

Events

NFC events arrive as handle_info messages:

handle_info({:nfc, :tag, %{tech: "Ndef", raw: "https://...", parsed: %{type: :url, value: "https://..."}}}, socket)
handle_info({:nfc, :error, %{reason: "NFC is disabled"}}, socket)

The parsed field is produced by Dala.Ui.Scan.parse/1 and contains a structured representation of the payload. See Dala.Ui.Scan for all supported formats (URL, WiFi, contact, email, phone, geo, text, calendar).

Platform notes

  • iOS: Uses NFCNDEFReaderSession. The system UI is shown automatically. Requires NFCReaderUsageDescription in Info.plist and the Near Field Communication Tag Reading capability.
  • Android: Uses NfcAdapter foreground dispatch. The hosting Activity must forward onNewIntent to DalaBridge.handleNFCIntent(intent). Requires android.permission.NFC in AndroidManifest.xml.

Usage

# Start scanning
Dala.Hardware.NFC.start_scan(socket, message: "Hold near a tag")

# Stop scanning
Dala.Hardware.NFC.stop_scan(socket)

# Check availability
Dala.Hardware.NFC.available?()

Parsing tag payloads

Use Dala.Ui.Scan.parse/1 to decode the raw payload into a structured format:

def handle_info({:nfc, :tag, %{raw: raw} = tag}, socket) do
  case Dala.Ui.Scan.parse(raw) do
    %{type: :url, value: url} ->
      # Open URL
    %{type: :wifi, value: %{ssid: ssid, password: pw}} ->
      # Connect to WiFi
    %{type: :text, value: text} ->
      # Plain text
  end
  {:noreply, socket}
end

Summary

Functions

available?()

Check if NFC is available and enabled on this device.

start_scan(socket, opts \\ [])

Start an NFC scan. The OS presents the scanning UI.

stop_scan(socket)

Stop the active NFC scan. Dismisses the iOS scanner UI.

Functions

available?()

@spec available?() :: boolean()

Check if NFC is available and enabled on this device.

start_scan(socket, opts \\ [])

@spec start_scan(
  Dala.Socket.t(),
  keyword()
) :: Dala.Socket.t()

Start an NFC scan. The OS presents the scanning UI.

Options:

  • message: String.t — prompt shown in the iOS NFC scanner UI (default: "Hold near an NFC tag"). Ignored on Android.

Tag reads arrive as {:nfc, :tag, %{tech: String.t, raw: String.t, parsed: map}}. The parsed field is nil if the payload format is not recognized by Dala.Ui.Scan.parse/1. Errors arrive as {:nfc, :error, %{reason: String.t}}.

stop_scan(socket)

@spec stop_scan(Dala.Socket.t()) :: Dala.Socket.t()

Stop the active NFC scan. Dismisses the iOS scanner UI.