修复拼写页 AttributeGraph 无限递归闪退

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

LearnEnglish/LearnEnglish/Views/SpellingWordInput.swift

@@ -1,11 +1,10 @@
 import SwiftUI
 import UIKit
 
-// Captures keystrokes one at a time via hidden UITextField delegate
 struct KeystrokeCaptureField: UIViewRepresentable {
     let onChar: (Character) -> Void
     let onBackspace: () -> Void
-    @Binding var isActive: Bool
+    let startActive: Bool
 
     func makeUIView(context: Context) -> UITextField {
         let tf = UITextField()
@@ -13,6 +12,7 @@ struct KeystrokeCaptureField: UIViewRepresentable {
         tf.autocorrectionType = .no
         tf.autocapitalizationType = .none
         tf.spellCheckingType = .no
+        context.coordinator.textField = tf
         return tf
     }
 
@@ -21,16 +21,17 @@ struct KeystrokeCaptureField: UIViewRepresentable {
     }
 
     func updateUIView(_ uiView: UITextField, context: Context) {
-        if isActive {
+        if startActive && !context.coordinator.didFocus {
             uiView.becomeFirstResponder()
-        } else {
-            uiView.resignFirstResponder()
+            context.coordinator.didFocus = true
         }
     }
 
     class Coordinator: NSObject, UITextFieldDelegate {
         let onChar: (Character) -> Void
         let onBackspace: () -> Void
+        weak var textField: UITextField?
+        var didFocus = false
 
         init(onChar: @escaping (Character) -> Void, onBackspace: @escaping () -> Void) {
             self.onChar = onChar
@@ -49,7 +50,6 @@ struct KeystrokeCaptureField: UIViewRepresentable {
     }
 }
 
-// Blinking cursor on the active blank
 struct BlinkingCursor: View {
     var body: some View {
         TimelineView(.periodic(from: .now, by: 0.6)) { timeline in
@@ -62,13 +62,11 @@ struct BlinkingCursor: View {
     }
 }
 
-// Interactive word input with per-blank slots
 struct SpellingWordInput: View {
     let blankedWord: String
     let blankPositions: [Int]
     @Binding var currentBlankIndex: Int
     @Binding var filledBlanks: [String]
-    @State private var isFocused = false
 
     private let chars: [String]
 
@@ -81,67 +79,59 @@ struct SpellingWordInput: View {
     }
 
     var body: some View {
-        VStack(spacing: 8) {
-            KeystrokeCaptureField(
-                onChar: { char in
-                    guard currentBlankIndex < blankPositions.count else { return }
-                    filledBlanks[currentBlankIndex] = String(char).lowercased()
-                    currentBlankIndex += 1
-                },
-                onBackspace: {
-                    guard currentBlankIndex > 0 else { return }
-                    currentBlankIndex -= 1
-                    filledBlanks[currentBlankIndex] = ""
-                },
-                isActive: $isFocused
-            )
-            .frame(width: 0, height: 0)
-
+        KeystrokeCaptureField(
+            onChar: { char in
+                guard currentBlankIndex < blankPositions.count else { return }
+                filledBlanks[currentBlankIndex] = String(char).lowercased()
+                currentBlankIndex += 1
+            },
+            onBackspace: {
+                guard currentBlankIndex > 0 else { return }
+                currentBlankIndex -= 1
+                filledBlanks[currentBlankIndex] = ""
+            },
+            startActive: true
+        )
+        .frame(width: 0, height: 0)
+        .overlay(alignment: .top) {
             HStack(spacing: 4) {
-                ForEach(Array(chars.enumerated()), id: \.offset) { index, ch in
-                    if ch == "_" {
-                        blankSlot(index: index)
-                    } else {
-                        Text(ch.uppercased())
-                            .font(.title2.weight(.bold))
-                            .frame(width: 22)
-                    }
+                ForEach(0..<chars.count, id: \.self) { index in
+                    charView(at: index)
                 }
             }
         }
-        .onTapGesture { isFocused = true }
-        .onAppear {
-            DispatchQueue.main.asyncAfter(deadline: .now() + 0.3) {
-                isFocused = true
-            }
-        }
     }
 
     @ViewBuilder
-    private func blankSlot(index: Int) -> some View {
-        let blankIndex = blankPositions.firstIndex(of: index) ?? 0
-        let isCurrent = blankIndex == currentBlankIndex && isFocused
-        let filled = blankIndex < filledBlanks.count ? filledBlanks[blankIndex] : nil
-
-        ZStack {
-            RoundedRectangle(cornerRadius: 6)
-                .fill(.quaternary.opacity(0.2))
-                .frame(width: 28, height: 40)
-            RoundedRectangle(cornerRadius: 6)
-                .stroke(.quaternary, lineWidth: 1)
-                .frame(width: 28, height: 40)
-            if isCurrent {
+    private func charView(at index: Int) -> some View {
+        let ch = chars[index]
+        if ch == "_" {
+            let blankIndex = blankPositions.firstIndex(of: index) ?? index
+            let isCurrent = blankIndex == currentBlankIndex
+            let filled = blankIndex < filledBlanks.count ? filledBlanks[blankIndex] : nil
+            ZStack {
+                RoundedRectangle(cornerRadius: 6)
+                    .fill(.quaternary.opacity(0.2))
+                    .frame(width: 28, height: 40)
+                RoundedRectangle(cornerRadius: 6)
+                    .stroke(.quaternary, lineWidth: 1)
+                    .frame(width: 28, height: 40)
+                    .opacity(isCurrent ? 0 : 1)
                 RoundedRectangle(cornerRadius: 6)
                     .stroke(.tint, lineWidth: 2)
                     .frame(width: 28, height: 40)
+                    .opacity(isCurrent ? 1 : 0)
+                if let filled, !filled.isEmpty {
+                    Text(filled.uppercased())
+                        .font(.title2.weight(.bold))
+                } else if isCurrent {
+                    BlinkingCursor()
+                }
             }
-
-            if let filled, !filled.isEmpty {
-                Text(filled.uppercased())
-                    .font(.title2.weight(.bold))
-            } else if isCurrent {
-                BlinkingCursor()
-            }
+        } else {
+            Text(ch.uppercased())
+                .font(.title2.weight(.bold))
+                .frame(width: 22)
         }
     }
 }