core-nfc

name core-nfc description Read and write NFC tags using CoreNFC. Use when scanning NDEF tags, reading ISO7816/ISO15693/FeliCa/MIFARE tags, writing NDEF messages, handling NFC session lifecycle, configuring NFC entitlements, or implementing background tag reading in iOS apps. CoreNFC Read and write NFC tags on iPhone using the CoreNFC framework. Covers NDEF reader sessions, tag reader sessions, NDEF message construction, entitlements, and background tag reading. Contents Setup NDEF Reader Session Tag Reader Session Writing NDEF Messages NDEF Payload Types Background Tag Reading Common Mistakes Review Checklist References Setup Project Configuration Add the Near Field Communication Tag Reading capability in Xcode Add NFCReaderUsageDescription to Info.plist with a user-facing reason string Add the com.apple.developer.nfc.readersession.formats entitlement with the current TAG value; do not add legacy NDEF For ISO 7816 tags, add supported application identifiers to com.apple.developer.nfc.readersession.iso7816.select-identifiers in Info.plist For FeliCa tags, add supported system codes to com.apple.developer.nfc.readersession.felica.systemcodes ; do not use wildcard system codes Device Requirements NFC reading requires iPhone 7 or later. Always check for reader session availability before creating NFC UI or sessions. Use the concrete reader session type you are about to create. import CoreNFC guard NFCNDEFReaderSession .readingAvailable else { // Device does not support NFC or feature is restricted showUnsupportedMessage() return } Key Types Type Role NFCNDEFReaderSession Scans for NDEF-formatted tags NFCTagReaderSession Scans for ISO7816, ISO15693, FeliCa, MIFARE tags NFCNDEFMessage Collection of NDEF payload records NFCNDEFPayload Single record within an NDEF message NFCNDEFTag Protocol for interacting with an NDEF-capable tag NDEF Reader Session Use NFCNDEFReaderSession to read NDEF-formatted data from tags. This is the simplest path for reading standard tag content like URLs, text, and MIME data. import CoreNFC final class NDEFReader : NSObject , NFCNDEFReaderSessionDelegate { private var session: NFCNDEFReaderSession ? func beginScanning () { guard NFCNDEFReaderSession .readingAvailable else { return } session = NFCNDEFReaderSession ( delegate: self , queue: nil , invalidateAfterFirstRead: false ) session ? .alertMessage = "Hold your iPhone near an NFC tag." session ? .begin() } // MARK: - NFCNDEFReaderSessionDelegate func readerSessionDidBecomeActive ( _ session : NFCNDEFReaderSession ) { // Session is scanning } func readerSession ( _ session : NFCNDEFReaderSession , didDetectNDEFs messages : [ NFCNDEFMessage ] ) { for message in messages { for record in message.records { processRecord(record) } } } func readerSession ( _ session : NFCNDEFReaderSession , didInvalidateWithError error : Error ) { let nfcError = error as? NFCReaderError if nfcError ? .code != .readerSessionInvalidationErrorFirstNDEFTagRead, nfcError ? .code != .readerSessionInvalidationErrorUserCanceled { print ( "Session invalidated: \(error.localizedDescription) " ) } self .session = nil } } Reading with Tag Connection For read-write operations, use the tag-detection delegate method to connect to individual tags: func readerSession ( _ session : NFCNDEFReaderSession , didDetect tags : [ any NFCNDEFTag ] ) { guard let tag = tags.first else { session.restartPolling() return } session.connect(to: tag) { error in if let error { session.invalidate(errorMessage: "Connection failed: \(error) " ) return } tag.queryNDEFStatus { status, capacity, error in guard error == nil else { session.invalidate(errorMessage: "Query failed." ) return } switch status { case .notSupported: session.invalidate(errorMessage: "Tag is not NDEF compliant." ) case .readOnly: tag.readNDEF { message, error in if let message { self .processMessage(message) } session.invalidate() } case .readWrite: tag.readNDEF { message, error in if let message { self .processMessage(message) } session.alertMessage = "Tag read successfully." session.invalidate() } @unknown default : session.invalidate() } } } } Tag Reader Session Use NFCTagReaderSession when you need direct access to the native tag protocol (ISO 7816, ISO 15693, FeliCa, or MIFARE). Polling option Tags .iso14443 ISO 7816-compatible and MIFARE .iso15693 ISO 15693 .iso18092 FeliCa Do not use this session for payment-related AIDs. Load nfc-patterns.md for protocol-specific connection, APDU, command, and response handling. Writing NDEF Messages Write NDEF data to a connected tag. Always check readWrite status first. func writeToTag ( tag : any NFCNDEFTag , session : NFCNDEFReaderSession , url : URL ) { tag.queryNDEFStatus { status, capacity, error in guard status == .readWrite else { session.invalidate(errorMessage: "Tag is read-only." ) return } guard let payload = NFCNDEFPayload .wellKnownTypeURIPayload( url: url ) else { session.invalidate(errorMessage: "Invalid URL." ) return } let message = NFCNDEFMessage (records: [payload]) tag.writeNDEF(message) { error in if let error { session.invalidate( errorMessage: "Write failed: \(error.localizedDescription) " ) } else { session.alertMessage = "Tag written successfully." session.invalidate() } } } } NDEF Payload Types Creating Common Payloads // URL payload let urlPayload = NFCNDEFPayload .wellKnownTypeURIPayload( url: URL (string: "https://example.com" ) ! ) // Text payload let textPayload = NFCNDEFPayload .wellKnownTypeTextPayload( string: "Hello NFC" , locale: Locale (identifier: "en" ) ) // Custom payload let customPayload = NFCNDEFPayload ( format: .nfcExternal, type: "com.example:mytype" .data(using: .utf8) ! , identifier: Data (), payload: "custom-data" .data(using: .utf8) ! ) Parsing Payload Content Load Parsing NDEF Payload Content for the complete type-name-format switch and multi-record handling. Background Tag Reading On iPhone XS and later, iOS can read NFC tags in the background without opening your app. The NDEF message must contain a URI record ( typeNameFormat == .nfcWellKnown , type U ). If there are multiple URI records, the system uses the first one. For app-specific routing, write a universal link to the tag and configure the Associated Domains capability for that domain. Background tag reading also supports specific system URL schemes such as web, email, SMS, telephone, FaceTime, Maps, and HomeKit setup. It does not support custom URL schemes, and the system does not route by bundle ID or arbitrary NDEF content type. When a user taps a compatible tag, iOS displays a notification that opens your app. Handle the tag data via NSUserActivity : func scene ( _ scene : UIScene , continue userActivity : NSUserActivity ) { guard userActivity.activityType == NSUserActivityTypeBrowsingWeb else { return } let message = userActivity.ndefMessagePayload guard message.records.first ? .typeNameFormat != .empty else { return } for record in message.records { processRecord(record) } } Common Mistakes DON'T: Use stale or missing NFC entitlements Without the com.apple.developer.nfc.readersession.formats entitlement, reader sessions cannot access NFC hardware. Use the current TAG value for Core NFC reader sessions; do not copy older examples that add NDEF . DON'T: Ignore session invalidation errors The session invalidates for multiple reasons. Distinguishing user cancellation from real errors prevents false error alerts. // WRONG -- shows error when user cancels func readerSession ( _ session : NFCNDEFReaderSession , didInvalidateWithError error : Error ) { showAlert( "NFC Error: \(error.localizedDescription) " ) } // CORRECT -- filter expected invalidation reasons func readerSession ( _ session : NFCNDEFReaderSession , didInvalidateWithError error : Error ) { let nfcError = error as? NFCReaderError switch nfcError ? .code { case .readerSessionInvalidationErrorUserCanceled, .readerSessionInvalidationErrorFirstNDEFTagRead: break // Normal termination default : showAlert( "NFC Error: \(error.localizedDescription) " ) } self .session = nil } DON'T: Hold a strong reference to a stale session Once a session is invalidated, it cannot be restarted. Nil out your reference and create a new session for the next scan. // WRONG -- reusing invalidated session func scanAgain () { session ? .begin() // Does nothing, session is dead } // CORRECT -- create a new session func scanAgain () { session = NFCNDEFReaderSession ( delegate: self , queue: nil , invalidateAfterFirstRead: false ) session ? .begin() } Review Checklist NFC capability added in Signing & Capabilities NFCReaderUsageDescription set in Info.plist com.apple.developer.nfc.readersession.formats entitlement uses TAG , not legacy NDEF NFCNDEFReaderSession.readingAvailable or NFCTagReaderSession.readingAvailable checked before creating sessions Session delegate set before calling begin() Session reference set to nil after invalidation didInvalidateWithError distinguishes user cancellation from actual errors NDEF status queried before write operations Tag capacity checked before writing large messages ISO 7816 application identifiers listed in Info.plist if using NFCTagReaderSession FeliCa system codes listed in Info.plist when polling .iso18092 Background tag reading uses a URI NDEF record and universal links or supported system URL schemes Custom URL schemes, bundle IDs, or arbitrary NDEF content types are not used for background routing Payment-related AIDs are routed away from NFCTagReaderSession Only one reader session active at a time References Extended patterns (ISO 7816 commands, multi-tag scanning, NDEF locking): references/nfc-patterns.md Core NFC framework NFCNDEFReaderSession NFCTagReaderSession NFCNDEFMessage NFCNDEFPayload NFCNDEFTag NFCNDEFReaderSessionDelegate NFCTagReaderSessionDelegate Building an NFC Tag-Reader App Adding Support for Background Tag Reading Near Field Communication Tag Reader Session Formats Entitlement ISO7816 application identifiers for NFC Tag Reader Session ISO18092 system codes for NFC Tag Reader Session