Fill in payments by scanning a QR code or picking one from photos

apps/ios/Koins/Info.plist

@@ -23,6 +23,8 @@
 		<key>NSAllowsArbitraryLoads</key>
 		<true/>
 	</dict>
+	<key>NSCameraUsageDescription</key>
+	<string>Scan a QR code to fill in a payment address.</string>
 	<key>UILaunchScreen</key>
 	<dict/>
 	<key>UISupportedInterfaceOrientations</key>

apps/ios/Koins/SelfTest.swift

@@ -122,6 +122,11 @@ enum SelfTest {
       emit("KOINS_SELFTEST \(name): \(ok ? "PASS" : "FAIL") \(actual)")
     }
 
+    func expectTrue(_ name: String, _ value: Bool) {
+      if !value { failures += 1 }
+      emit("KOINS_SELFTEST \(name): \(value ? "PASS" : "FAIL")")
+    }
+
     expect("ripemd160", Hex.encode(RIPEMD160.hash(Array("abc".utf8))),
            "8eb208f7e05d987a9b044a8e98c6b087f15a0bfc")
 
@@ -236,6 +241,55 @@ enum SelfTest {
       }
     }
 
+    // QR round trip: generate an image, read it back, parse the payment URI.
+    let xmrAddress = "46cRPeU77sBVGSVXPyCjvJUdC9AjqvETWb6giUGskdnWN8ZifindmrH7mcztKU52iKgvWXY4dyPujg9LYUY1Q7dvDiwHNCE"
+    let xrpAddress = "rHR6xtDW7BxeQN8VB8R9HzXzyMeS42n7C"
+
+    func roundTrip(_ name: String, _ text: String, checks: [(String, String)]) {
+      guard let image = QRCodeImage.make(text) else {
+        failures += 1
+        emit("KOINS_SELFTEST \(name): FAIL could not render QR image")
+        return
+      }
+      guard let decoded = QRCodeReader.decodeText(in: image) else {
+        failures += 1
+        emit("KOINS_SELFTEST \(name): FAIL vision could not read the QR image (\(Int(image.size.width))px)")
+        return
+      }
+      guard let payload = QRCodeReader.parse(decoded) else {
+        failures += 1
+        emit("KOINS_SELFTEST \(name): FAIL parse of '\(decoded)'")
+        return
+      }
+      for (label, expected) in checks {
+        let actual: String
+        switch label {
+        case "address": actual = payload.address
+        case "amount": actual = payload.amount ?? ""
+        case "tag": actual = payload.tag.map(String.init) ?? ""
+        case "paymentId": actual = payload.paymentId ?? ""
+        case "memo": actual = payload.memo ?? ""
+        default: actual = ""
+        }
+        expect("\(name) \(label)", actual, expected)
+      }
+    }
+
+    roundTrip("qr monero uri",
+              "monero:\(xmrAddress)?tx_amount=1.5&tx_payment_id=abc123&tx_description=Rent",
+              checks: [("address", xmrAddress), ("amount", "1.5"), ("paymentId", "abc123"), ("memo", "Rent")])
+    roundTrip("qr monero plain", xmrAddress, checks: [("address", xmrAddress)])
+    roundTrip("qr xrp uri",
+              "ripple:\(xrpAddress)?amount=12.5&dt=99",
+              checks: [("address", xrpAddress), ("amount", "12.5"), ("tag", "99")])
+    roundTrip("qr xrp plain", xrpAddress, checks: [("address", xrpAddress)])
+
+    expectTrue("qr monero detected", AddressFormat.isMonero(xmrAddress))
+    expectTrue("qr xrp detected", AddressFormat.isXRP(xrpAddress))
+    expectTrue("qr rejects junk", QRCodeReader.parse("hello world")?.address == "hello world")
+    expectTrue("qr not monero", !AddressFormat.isMonero(xrpAddress))
+    expectTrue("qr not xrp", !AddressFormat.isXRP(xmrAddress))
+
     // secp256k1 signing must produce a low-S DER signature.
     if let keypair = try? XRPKey.keypair(fromSeed: secpSeed),
        let message = Hex.decode(signingHex),

apps/ios/Koins/Support/QRCodeReader.swift

@@ -0,0 +1,135 @@
+import CoreImage
+import CoreImage.CIFilterBuiltins
+import Foundation
+import UIKit
+import Vision
+
+/// Renders a QR image (used by the UI and by the self-test, which round-trips
+/// an image through the reader).
+enum QRCodeImage {
+  static func make(_ text: String, scale: CGFloat = 10) -> UIImage? {
+    guard !text.isEmpty else { return nil }
+    let filter = CIFilter.qrCodeGenerator()
+    filter.message = Data(text.utf8)
+    filter.correctionLevel = "M"
+    guard let output = filter.outputImage else { return nil }
+    let scaled = output.transformed(by: CGAffineTransform(scaleX: scale, y: scale))
+    let context = CIContext()
+    guard let cgImage = context.createCGImage(scaled, from: scaled.extent) else { return nil }
+    return UIImage(cgImage: cgImage)
+  }
+}
+
+/// A payment request decoded from a QR code: the address plus whatever else the
+/// code carried.
+struct QRPayload {
+  var address: String
+  var amount: String?
+  var tag: UInt32?
+  var paymentId: String?
+  var memo: String?
+}
+
+enum QRCodeReader {
+  /// Reads the first QR code found in an image (used for photo-library import).
+  static func decodeText(in data: Data) -> String? {
+    guard let image = UIImage(data: data), let cgImage = image.cgImage else { return nil }
+    return decodeText(in: cgImage)
+  }
+
+  static func decodeText(in image: UIImage) -> String? {
+    guard let cgImage = image.cgImage else { return nil }
+    return decodeText(in: cgImage)
+  }
+
+  private static func decodeText(in cgImage: CGImage) -> String? {
+    if let text = decodeWithVision(cgImage) { return text }
+    // Vision's barcode detector does not work on the iOS simulator, so fall
+    // back to CoreImage, which does (and adds redundancy on device).
+    return decodeWithCoreImage(cgImage)
+  }
+
+  private static func decodeWithVision(_ cgImage: CGImage) -> String? {
+    let request = VNDetectBarcodesRequest()
+    request.symbologies = [.qr]
+    let handler = VNImageRequestHandler(cgImage: cgImage, orientation: .up)
+    try? handler.perform([request])
+    for observation in request.results ?? [] {
+      if let payload = observation.payloadStringValue, !payload.isEmpty {
+        return payload
+      }
+    }
+    return nil
+  }
+
+  private static func decodeWithCoreImage(_ cgImage: CGImage) -> String? {
+    let detector = CIDetector(ofType: CIDetectorTypeQRCode,
+                              context: nil,
+                              options: [CIDetectorAccuracy: CIDetectorAccuracyHigh])
+    let features = detector?.features(in: CIImage(cgImage: cgImage)) ?? []
+    for feature in features {
+      if let code = feature as? CIQRCodeFeature, let message = code.messageString, !message.isEmpty {
+        return message
+      }
+    }
+    return nil
+  }
+
+  /// Understands plain addresses as well as the payment URIs wallets emit:
+  /// `monero:` (tx_amount, tx_payment_id, tx_description) and `ripple:`
+  /// (amount, dt).
+  static func parse(_ raw: String) -> QRPayload? {
+    let text = raw.trimmingCharacters(in: .whitespacesAndNewlines)
+    guard !text.isEmpty else { return nil }
+
+    var body = text
+    var query: [String: String] = [:]
+
+    if let separator = text.firstIndex(of: "?") {
+      body = String(text[text.startIndex..<separator])
+      let queryText = String(text[text.index(after: separator)...])
+      for pair in queryText.split(separator: "&") {
+        let parts = pair.split(separator: "=", maxSplits: 1)
+        guard let key = parts.first else { continue }
+        let value = parts.count > 1 ? String(parts[1]) : ""
+        query[key.lowercased()] = value.removingPercentEncoding ?? value
+      }
+    }
+
+    let lowered = body.lowercased()
+    if let range = lowered.range(of: "monero:") {
+      body = String(body[range.upperBound...])
+    } else if let range = lowered.range(of: "ripple:") {
+      body = String(body[range.upperBound...])
+    }
+    while body.hasPrefix("/") { body.removeFirst() }
+
+    let address = body.trimmingCharacters(in: .whitespacesAndNewlines)
+    guard !address.isEmpty else { return nil }
+
+    var payload = QRPayload(address: address)
+    payload.amount = query["tx_amount"] ?? query["amount"]
+    payload.memo = query["tx_description"] ?? query["name"] ?? query["message"]
+    payload.paymentId = query["tx_payment_id"] ?? query["payment_id"] ?? query["pid"]
+    if let tag = query["dt"] ?? query["destination_tag"] ?? query["destinationtag"] {
+      payload.tag = UInt32(tag)
+    }
+    return payload
+  }
+}
+
+enum AddressFormat {
+  private static let moneroAlphabet = Set("123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz")
+
+  /// Monero addresses are 95 characters (primary/subaddress) or 106
+  /// (integrated), all base58.
+  static func isMonero(_ address: String) -> Bool {
+    let text = address.trimmingCharacters(in: .whitespacesAndNewlines)
+    guard text.count == 95 || text.count == 106 else { return false }
+    return text.allSatisfy { moneroAlphabet.contains($0) }
+  }
+
+  static func isXRP(_ address: String) -> Bool {
+    XRPKey.isValidAddress(address.trimmingCharacters(in: .whitespacesAndNewlines))
+  }
+}

apps/ios/Koins/Views/Components.swift

@@ -166,15 +166,7 @@ struct QRCodeView: View {
   }
 
   private static func makeImage(from text: String) -> UIImage? {
-    guard !text.isEmpty else { return nil }
+    QRCodeImage.make(text)
-    let filter = CIFilter.qrCodeGenerator()
-    filter.message = Data(text.utf8)
-    filter.correctionLevel = "M"
-    guard let output = filter.outputImage else { return nil }
-    let scaled = output.transformed(by: CGAffineTransform(scaleX: 10, y: 10))
-    let context = CIContext()
-    guard let cgImage = context.createCGImage(scaled, from: scaled.extent) else { return nil }
-    return UIImage(cgImage: cgImage)
   }
 }
 

apps/ios/Koins/Views/DashboardViews.swift

@@ -1,3 +1,4 @@
+import PhotosUI
 import SwiftUI
 
 struct DashboardView: View {
@@ -124,6 +125,9 @@ struct SendView: View {
   @State private var tag = ""
   @State private var priority: TransactionPriority = .defaultPriority
   @State private var localError: String?
+  @State private var status: String?
+  @State private var showScanner = false
+  @State private var photoItem: PhotosPickerItem?
 
   var body: some View {
     VStack(alignment: .leading, spacing: 18) {
@@ -131,6 +135,20 @@ struct SendView: View {
                    subtitle: "Balance \(model.balance.total) \(model.symbol)",
                    onBack: { route = .home })
 
+      HStack(spacing: 10) {
+        SecondaryButton(title: "Scan QR") { showScanner = true }
+        PhotosPicker(selection: $photoItem, matching: .images, photoLibrary: .shared()) {
+          Text("Photo")
+            .font(.system(size: 15, weight: .medium))
+            .frame(maxWidth: .infinity)
+            .padding(.vertical, 14)
+            .background(Theme.surface)
+            .foregroundStyle(Theme.text)
+            .overlay(RoundedRectangle(cornerRadius: 14, style: .continuous).stroke(Theme.border))
+            .clipShape(RoundedRectangle(cornerRadius: 14, style: .continuous))
+        }
+      }
+
       VStack(alignment: .leading, spacing: 6) {
         FieldLabel(text: model.chain == .xrp ? "Destination address" : "Recipient address")
         KoinsTextField(placeholder: model.chain == .xrp ? "r…" : "4…", text: $destination)
@@ -163,6 +181,9 @@ struct SendView: View {
       if let message = localError ?? model.errorMessage {
         MessageBanner(message: message, isError: true)
       }
+      if let message = status {
+        MessageBanner(message: message, isError: false)
+      }
       if let message = model.statusMessage {
         MessageBanner(message: message, isError: false)
       }
@@ -184,6 +205,65 @@ struct SendView: View {
 
       Spacer(minLength: 0)
     }
+    .sheet(isPresented: $showScanner) {
+      QRScannerView(onScan: { value in
+        showScanner = false
+        applyScanned(value)
+      }, onCancel: {
+        showScanner = false
+      })
+      .ignoresSafeArea()
+    }
+    .onChange(of: photoItem) { item in
+      guard let item else { return }
+      Task {
+        if let data = try? await item.loadTransferable(type: Data.self) {
+          if let value = QRCodeReader.decodeText(in: data) {
+            applyScanned(value)
+          } else {
+            localError = "No QR code found in that image"
+          }
+        } else {
+          localError = "That image could not be read"
+        }
+        photoItem = nil
+      }
+    }
+  }
+
+  /// Fills the form from a scanned code, accepting both plain addresses and
+  /// wallet payment URIs (`monero:…?tx_amount=`, `ripple:…?amount=&dt=`).
+  private func applyScanned(_ value: String) {
+    localError = nil
+    status = nil
+    guard let payload = QRCodeReader.parse(value) else {
+      localError = "That QR code is not a payment request"
+      return
+    }
+
+    let isForThisChain = model.chain == .xrp
+      ? AddressFormat.isXRP(payload.address)
+      : AddressFormat.isMonero(payload.address)
+    guard isForThisChain else {
+      localError = model.chain == .xrp
+        ? "That looks like a Monero address. Switch to Monero to use it."
+        : "That looks like an XRP address. Switch to XRP to use it."
+      return
+    }
+
+    destination = payload.address
+    if let scannedAmount = payload.amount, !scannedAmount.isEmpty {
+      amount = scannedAmount
+    }
+    if model.chain == .xrp, let scannedTag = payload.tag {
+      tag = String(scannedTag)
+    }
+
+    var filled: [String] = ["address"]
+    if payload.amount?.isEmpty == false { filled.append("amount") }
+    if payload.tag != nil { filled.append("tag") }
+    if payload.paymentId?.isEmpty == false { filled.append("payment ID") }
+    status = "Filled \(filled.joined(separator: ", ")) from the QR code"
   }
 }
 

apps/ios/Koins/Views/QRScannerView.swift

@@ -0,0 +1,141 @@
+import AVFoundation
+import SwiftUI
+
+/// Camera QR scanner, presented as a sheet. On a simulator (no capture device)
+/// it explains that instead of showing a dead viewfinder.
+struct QRScannerView: UIViewControllerRepresentable {
+  var onScan: (String) -> Void
+  var onCancel: () -> Void
+
+  func makeUIViewController(context: Context) -> ScannerViewController {
+    let controller = ScannerViewController()
+    controller.onScan = onScan
+    controller.onCancel = onCancel
+    return controller
+  }
+
+  func updateUIViewController(_ controller: ScannerViewController, context: Context) {}
+}
+
+final class ScannerViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
+  var onScan: ((String) -> Void)?
+  var onCancel: (() -> Void)?
+
+  private let session = AVCaptureSession()
+  private var previewLayer: AVCaptureVideoPreviewLayer?
+  private var hasScanned = false
+  private var messageLabel: UILabel?
+
+  override func viewDidLoad() {
+    super.viewDidLoad()
+    view.backgroundColor = .black
+
+    let cancel = UIButton(type: .system)
+    cancel.setTitle("Cancel", for: .normal)
+    cancel.setTitleColor(.white, for: .normal)
+    cancel.titleLabel?.font = .systemFont(ofSize: 16, weight: .semibold)
+    cancel.addTarget(self, action: #selector(cancelTapped), for: .touchUpInside)
+    cancel.translatesAutoresizingMaskIntoConstraints = false
+    view.addSubview(cancel)
+    NSLayoutConstraint.activate([
+      cancel.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 12),
+      cancel.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20),
+    ])
+
+    let label = UILabel()
+    label.numberOfLines = 0
+    label.textAlignment = .center
+    label.textColor = .white
+    label.font = .systemFont(ofSize: 14)
+    label.translatesAutoresizingMaskIntoConstraints = false
+    view.addSubview(label)
+    NSLayoutConstraint.activate([
+      label.centerYAnchor.constraint(equalTo: view.centerYAnchor),
+      label.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 32),
+      label.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -32),
+    ])
+    messageLabel = label
+
+    requestCamera()
+  }
+
+  override func viewDidLayoutSubviews() {
+    super.viewDidLayoutSubviews()
+    previewLayer?.frame = view.bounds
+  }
+
+  override func viewWillDisappear(_ animated: Bool) {
+    super.viewWillDisappear(animated)
+    if session.isRunning { session.stopRunning() }
+  }
+
+  @objc private func cancelTapped() {
+    onCancel?()
+  }
+
+  private func requestCamera() {
+    guard let device = AVCaptureDevice.default(for: .video) else {
+      showMessage("This device has no camera. Use “Photo” to pick a QR from the library instead.")
+      return
+    }
+
+    switch AVCaptureDevice.authorizationStatus(for: .video) {
+    case .authorized:
+      configure(device: device)
+    case .notDetermined:
+      AVCaptureDevice.requestAccess(for: .video) { [weak self] granted in
+        DispatchQueue.main.async {
+          if granted {
+            self?.configure(device: device)
+          } else {
+            self?.showMessage("Camera access is off. Enable it in Settings, or use “Photo”.")
+          }
+        }
+      }
+    default:
+      showMessage("Camera access is off. Enable it in Settings, or use “Photo”.")
+    }
+  }
+
+  private func configure(device: AVCaptureDevice) {
+    guard let input = try? AVCaptureDeviceInput(device: device), session.canAddInput(input) else {
+      showMessage("The camera could not be started. Use “Photo” instead.")
+      return
+    }
+    session.addInput(input)
+
+    let output = AVCaptureMetadataOutput()
+    guard session.canAddOutput(output) else {
+      showMessage("The camera could not be started. Use “Photo” instead.")
+      return
+    }
+    session.addOutput(output)
+    output.setMetadataObjectsDelegate(self, queue: .main)
+    output.metadataObjectTypes = [.qr]
+
+    let layer = AVCaptureVideoPreviewLayer(session: session)
+    layer.videoGravity = .resizeAspectFill
+    layer.frame = view.bounds
+    view.layer.insertSublayer(layer, at: 0)
+    previewLayer = layer
+
+    DispatchQueue.global(qos: .userInitiated).async { [weak self] in
+      self?.session.startRunning()
+    }
+  }
+
+  private func showMessage(_ text: String) {
+    messageLabel?.text = text
+  }
+
+  func metadataOutput(_ output: AVCaptureMetadataOutput,
+                      didOutput metadataObjects: [AVMetadataObject],
+                      from connection: AVCaptureConnection) {
+    guard !hasScanned else { return }
+    guard let object = metadataObjects.first as? AVMetadataMachineReadableCodeObject,
+          let value = object.stringValue, !value.isEmpty else { return }
+    hasScanned = true
+    session.stopRunning()
+    onScan?(value)
+  }
+}

apps/ios/Koins/Views/RootView.swift

@@ -19,8 +19,15 @@ struct SeedBox: Identifiable {
 struct RootView: View {
   @EnvironmentObject private var model: AppModel
   @Environment(\.scenePhase) private var scenePhase
-  @State private var route: Route = ProcessInfo.processInfo.arguments.contains("-koinsScreenAccounts")
+  @State private var route: Route = RootView.initialRoute
-    ? .accounts : .home
+
+  private static var initialRoute: Route {
+    let arguments = ProcessInfo.processInfo.arguments
+    if arguments.contains("-koinsScreenAccounts") { return .accounts }
+    if arguments.contains("-koinsScreenSend") { return .send }
+    if arguments.contains("-koinsScreenReceive") { return .receive }
+    return .home
+  }
   @State private var seedBox: SeedBox?
 
   var body: some View {

apps/ios/project.yml

@@ -65,6 +65,7 @@ targets:
         UISupportedInterfaceOrientations:
           - UIInterfaceOrientationPortrait
         UIUserInterfaceStyle: Dark
+        NSCameraUsageDescription: Scan a QR code to fill in a payment address.
         NSAppTransportSecurity:
           NSAllowsArbitraryLoads: true