Show Tailscale sign-in in an in-app web view

mac/Sources/Byre/Tailnet.swift

@@ -3,6 +3,9 @@ import Network
 import Observation
 import SwiftUI
 import TailscaleKit
+#if os(iOS)
+import SafariServices
+#endif
 
 func slug(_ text: String) -> String {
     var out = ""
@@ -288,6 +291,7 @@ private struct NodeLoginRow: View {
     let role: String
     let state: String
     let authURL: URL?
+    @State private var signingIn = false
 
     var body: some View {
         HStack(alignment: .center, spacing: 12) {
@@ -307,9 +311,13 @@ private struct NodeLoginRow: View {
             .frame(maxWidth: .infinity, alignment: .leading)
             if state != "Running" {
                 Button("Sign in") {
+                    #if os(macOS)
                     if let authURL {
                         openExternal(authURL)
                     }
+                    #else
+                    signingIn = true
+                    #endif
                 }
                 .buttonStyle(WebButtonStyle(primary: true))
                 .disabled(authURL == nil)
@@ -319,5 +327,30 @@ private struct NodeLoginRow: View {
         .padding(12)
         .background(Palette.bg, in: RoundedRectangle(cornerRadius: 8))
         .overlay(RoundedRectangle(cornerRadius: 8).stroke(Palette.border))
+        #if os(iOS)
+        .sheet(isPresented: $signingIn) {
+            if let authURL {
+                SafariView(url: authURL)
+                    .ignoresSafeArea()
+            }
+        }
+        .onChange(of: state) {
+            if state == "Running" {
+                signingIn = false
+            }
+        }
+        #endif
     }
 }
+
+#if os(iOS)
+private struct SafariView: UIViewControllerRepresentable {
+    let url: URL
+
+    func makeUIViewController(context: Context) -> SFSafariViewController {
+        SFSafariViewController(url: url)
+    }
+
+    func updateUIViewController(_ controller: SFSafariViewController, context: Context) {}
+}
+#endif