====== Barcode Scanner ======

The Scan tab lets you scan drug barcodes with your device's camera to instantly look up NDC codes. This feature is available on iPhone and iPad only (not on Mac).

===== How to Scan =====

  - Tap the **Scan** tab
  - Point your camera at the barcode on a drug package
  - The app detects the barcode and decodes the NDC automatically
  - If a match is found, the product appears below the camera view
  - Tap the product to view the full [[ndc-lookup:product-detail|product detail]]

===== Supported Barcodes =====

NDC Lookup supports:

  * **UPC-A** — The standard 12-digit barcode found on most US drug packaging
  * **EAN-13** — The international 13-digit barcode format (UPC-A is a subset)

===== How UPC-to-NDC Conversion Works =====

Drug barcodes use UPC-A codes that encode the NDC with a prefix and check digit:

  - The UPC starts with a **3** prefix (indicating a pharmaceutical product)
  - The next **10 digits** are the NDC
  - The last digit is a **check digit**

The app strips the prefix and check digit to extract the 10-digit NDC, then searches the database for matching packages.

===== Camera Permission =====

The app requires camera access to scan barcodes. On first use, iOS will prompt you to allow camera access. If you denied access, you can enable it in:

**Settings > NDC Lookup > Camera**

===== Scan Again =====

After a scan, tap **Scan Again** to reset and scan another barcode.

**Tip:**
For best results, hold the camera steady about 6-8 inches from the barcode in good lighting. The barcode should fill most of the camera frame.