NFC Reader/Writer App

A Flutter application that reads and writes NFC NDEF tags using the flutter_nfc_kit package. Supports both Android and iOS platforms.

Features

• ✅ Check NFC availability before scanning
• ✅ Read NFC tag UID and NDEF records
• ✅ Display tag ID, type, and payload information
• ✅ Write NDEF URL records to NFC tags
• ✅ Graceful error handling for timeouts and user cancellation
• ✅ Proper NFC session management
• ✅ Clean architecture with service layer separation
• ✅ Material Design UI with modern Flutter practices

Prerequisites

• Flutter SDK (3.9.2 or higher)
• Android Studio / Xcode (for platform-specific setup)
• Physical device with NFC support (NFC cannot be tested on emulators)

Installation

1. Clone the repository and navigate to the project directory:

cd nfc_app

2. Install dependencies:

flutter pub get

Platform-Specific Setup

Android Setup

The Android configuration is already set up in android/app/src/main/AndroidManifest.xml:

• ✅ NFC permission (android.permission.NFC)
• ✅ NFC feature declaration (optional, not required)

Additional Steps:

1. Minimum SDK Version: Ensure your android/app/build.gradle.kts has a minimum SDK version of 21 or higher:

   android {
       defaultConfig {
           minSdk = 21  // or higher
       }
   }

2. Enable NFC on Device:

   • Go to Settings → Connected devices → Connection preferences → NFC
   • Ensure NFC is enabled

3. Testing:

   • NFC operations require a physical Android device
   • NFC cannot be tested on Android emulators
   • Ensure your device supports NFC (most modern Android devices do)

iOS Setup

The iOS configuration has been set up with:

• ✅ NFCReaderUsageDescription in Info.plist
• ✅ com.apple.developer.nfc.readersession.formats in Info.plist
• ✅ Runner.entitlements file with NFC capability

CRITICAL: Xcode Configuration Steps (Required for NFC to Work)

You MUST complete these steps in Xcode for NFC to work on iOS:

1. Open the Project in Xcode:

   open ios/Runner.xcworkspace

   ⚠️ Important: Open .xcworkspace, NOT .xcodeproj

2. Add NFC Capability:

   • In Xcode, select the Runner project in the left sidebar
   • Select the Runner target (under TARGETS)
   • Click the "Signing & Capabilities" tab
   • Click the "+ Capability" button (top left of the capabilities section)
   • Search for and add "Near Field Communication Tag Reading"
   • Verify that the capability appears with a checkmark

3. Link Entitlements File (if not automatically done):

   • Still in "Signing & Capabilities" tab
   • Look for "Code Signing Entitlements" field
   • If empty, enter: Runner/Runner.entitlements
   • Xcode should automatically link it when you add the capability, but verify it's set

4. Verify Build Settings:

   • Go to "Build Settings" tab
   • Search for "Code Signing Entitlements"
   • Ensure it shows: Runner/Runner.entitlements (for all configurations: Debug, Release, Profile)

5. Clean and Rebuild:

   cd ios
   rm -rf Pods Podfile.lock
   pod install
   cd ..
   flutter clean
   flutter pub get

6. Minimum iOS Version:

   • iOS 11.0 or higher is required for NFC functionality
   • Your project is already configured for iOS 13.0+ (see IPHONEOS_DEPLOYMENT_TARGET)

Why NFC Availability Check Fails Without This Setup:

On iOS, FlutterNfcKit.nfcAvailability will return notAvailable or throw an exception if:

• The NFC capability is not added in Xcode
• The entitlements file is not linked to the target
• The app is not signed with NFC entitlements
• NFCReaderUsageDescription is missing from Info.plist

Even on iPhone 13 Pro (which definitely supports NFC), the availability check will fail without proper Xcode configuration.

Testing:

• NFC operations require a physical iOS device (iPhone 7 or later)
• NFC cannot be tested on iOS simulators
• After completing Xcode setup, rebuild and test on a real device

Running the App

1. Connect a physical device with NFC support
2. Ensure NFC is enabled on the device
3. Run the app:

flutter run

Usage

Reading NFC Tags

1. Tap the "Read Tag" button
2. Hold your device near an NFC tag
3. The app will display:
   • Tag ID (UID)
   • Tag Type (NFC-A, NFC-B, etc.)
   • NDEF Records (if available)

Writing to NFC Tags

1. Tap the "Write URL" button
2. Enter a URL in the dialog (e.g., https://example.com)
3. Hold your device near a writable NFC tag
4. The app will write the URL as an NDEF record

Project Structure

lib/
├── main.dart                 # Main UI and app entry point
└── services/
    └── nfc_service.dart      # NFC service class with read/write logic

Key Components

NfcService (lib/services/nfc_service.dart)

Service class that handles all NFC operations:

• isNfcAvailable(): Checks if NFC is available on the device
• readTag(): Reads tag UID and NDEF records
• writeUrl(String url): Writes a URL as an NDEF record
• cancel(): Cancels ongoing NFC operations

Main UI (lib/main.dart)

Material Design UI with:

• NFC availability status indicator
• Read and Write buttons
• Tag information display
• Error handling and user feedback
• Loading states during NFC operations

Error Handling

The app handles various error scenarios:

• NFC not available or disabled
• Timeout while waiting for tag
• User cancellation
• Tag read/write failures
• Invalid tag types

All errors are displayed to the user with clear messages.

NFC Session Management

The app properly manages NFC sessions:

• Sessions are automatically closed after each operation
• Sessions are cancelled when the user navigates away
• Proper cleanup in dispose() method

Troubleshooting

Android Issues

• "NFC is not available":

  • Check if NFC is enabled in device settings
  • Ensure you're testing on a physical device (not emulator)
  • Verify your device has NFC hardware

• "Error reading tag":

  • Ensure the tag is close enough to the device
  • Try holding the tag steady for a few seconds
  • Some tags may not support NDEF format

iOS Issues

• "NFC is not available" (Most Common Issue):

  Root Cause: Missing NFC capability or entitlements configuration in Xcode.

  Solution:

  1. Open ios/Runner.xcworkspace in Xcode
  2. Select Runner target → "Signing & Capabilities" tab
  3. Add "Near Field Communication Tag Reading" capability
  4. Verify Runner/Runner.entitlements is linked in "Code Signing Entitlements"
  5. Clean build folder: Product → Clean Build Folder (⇧⌘K)
  6. Rebuild: flutter clean && flutter pub get && flutter run

  Verification Steps:

  • Check that Runner.entitlements exists in ios/Runner/
  • Verify it contains com.apple.developer.nfc.readersession.formats
  • Ensure Info.plist has NFCReaderUsageDescription
  • Confirm the capability appears in Xcode's "Signing & Capabilities" tab

• "NFC is not available" on iPhone 13 Pro or other supported devices:

  • This is always a configuration issue, not a hardware issue
  • iPhone 7 and later models support NFC
  • The problem is missing Xcode capability setup (see above)

• Build errors:

  • Clean and rebuild: flutter clean && flutter pub get
  • Reinstall pods: cd ios && rm -rf Pods Podfile.lock && pod install && cd ..
  • Ensure Xcode has the NFC capability enabled
  • Check that minimum iOS version is 11.0+ (your project uses 13.0+)

• Entitlements not found error:

  • Verify Runner.entitlements file exists at ios/Runner/Runner.entitlements
  • Check that it's added to the Xcode project (should appear in file navigator)
  • Ensure "Code Signing Entitlements" build setting points to Runner/Runner.entitlements

Dependencies

• flutter_nfc_kit: ^5.0.0 - NFC functionality for Flutter

License

This project is a Flutter application template.

Notes

• NFC operations require physical devices - emulators/simulators do not support NFC
• Some NFC tags may be read-only and cannot be written to
• The app uses a 30-second timeout for NFC operations
• NDEF URL records use the standard format with prefix codes (0x04 for https://)