修复大小写切换后新输入字母不跟随转换，输入时根据当前大小写状态存储

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

LearnEnglish/LearnEnglish/Models/Quiz.swift

@@ -51,6 +51,27 @@ enum QuizGenerator {
         }
     }
 
+    static func recase(_ questions: [QuizQuestion], toUpper: Bool) -> [QuizQuestion] {
+        questions.map { q in
+            let word = q.word
+            let text = toUpper ? word.word.uppercased() : word.word.lowercased()
+            let recased = Word(categoryId: word.categoryId, word: text, phonetic: word.phonetic,
+                               meaning: word.meaning, example: word.example, exampleMeaning: word.exampleMeaning)
+            let blanked = q.blankedWord.map { ch -> String in
+                ch == "_" ? "_" : ch.uppercased()
+            }.joined()
+            let blankedWord = toUpper ? blanked.uppercased() : blanked.lowercased()
+            return QuizQuestion(
+                word: recased,
+                prompt: q.prompt,
+                options: q.options,
+                answer: text,
+                blankedWord: blankedWord,
+                blankPositions: q.blankPositions
+            )
+        }
+    }
+
     private static func promptText(_ word: Word, _ mode: QuizMode) -> String {
         switch mode {
         case .enToZh: return word.word

LearnEnglish/LearnEnglish/Views/QuizViewController.swift

@@ -218,6 +218,7 @@ final class QuizViewController: UIViewController {
 
         if isSpelling {
             spellingHintLabel.text = "\(question.word.word.count) 个字母，补全空缺部分"
+            spellingView.isUppercase = isUppercase
             spellingView.configure(blankedWord: question.blankedWord, blankPositions: question.blankPositions)
             if config.isStudyMode {
                 nextButton.isHidden = true
@@ -425,7 +426,9 @@ final class QuizViewController: UIViewController {
         isUppercase.toggle()
         UserDefaults.standard.set(isUppercase, forKey: "spelling_uppercase")
         updateCaseButton()
-        restart()
+        spellingView.isUppercase = isUppercase
+        questions = QuizGenerator.recase(questions, toUpper: isUppercase)
+        spellingView.updateCase(toUpper: isUppercase)
     }
 
     private func updateCaseButton() {

LearnEnglish/LearnEnglish/Views/SpellingInputView.swift

@@ -17,6 +17,8 @@ final class SpellingInputView: UIView, UITextFieldDelegate {
     private var cursorView: UIView?
     private var inputEnabled = true
 
+    var isUppercase = false
+
     var isComplete: Bool {
         !filledBlanks.isEmpty && filledBlanks.allSatisfy { !$0.isEmpty }
     }
@@ -133,6 +135,20 @@ final class SpellingInputView: UIView, UITextFieldDelegate {
         hiddenField.inputAccessoryView = nil
     }
 
+    func updateCase(toUpper: Bool) {
+        chars = chars.map {
+            guard $0 != "_" else { return $0 }
+            return toUpper ? $0.uppercased() : $0.lowercased()
+        }
+        filledBlanks = filledBlanks.map {
+            $0.isEmpty ? $0 : (toUpper ? $0.uppercased() : $0.lowercased())
+        }
+        for (index, box) in boxViews.enumerated() where chars[index] != "_" {
+            (box.viewWithTag(100) as? UILabel)?.text = chars[index]
+        }
+        refreshBoxes()
+    }
+
     func showResultState(correct: Bool) {
         let color = correct ? Theme.Color.correct : Theme.Color.wrong
         for position in blankPositions {
@@ -169,7 +185,8 @@ final class SpellingInputView: UIView, UITextFieldDelegate {
                 onChange?()
             }
         } else if let char = string.last, char.isLetter, cursorIndex < blankPositions.count {
-            filledBlanks[cursorIndex] = String(char).lowercased()
+            let converted = isUppercase ? char.uppercased() : char.lowercased()
+            filledBlanks[cursorIndex] = converted
             cursorIndex += 1
             refreshBoxes()
             popBox(atBlank: cursorIndex - 1)

LearnEnglish/LearnEnglish/Views/WordDetailViewController.swift

@@ -32,8 +32,8 @@ final class WordDetailViewController: UIViewController {
         title = categoryName
         navigationItem.largeTitleDisplayMode = .never
         navigationItem.rightBarButtonItems = [
-            UIBarButtonItem(image: UIImage(systemName: "clock.arrow.circlepath"), style: .plain, target: self, action: #selector(showHistory)),
-            UIBarButtonItem(title: "学习", style: .plain, target: self, action: #selector(startSpelling))
+            UIBarButtonItem(title: "学习", style: .plain, target: self, action: #selector(startSpelling)),
+            UIBarButtonItem(image: UIImage(systemName: "clock.arrow.circlepath"), style: .plain, target: self, action: #selector(showHistory))
         ]
         buildLayout()
         updateSpeakState()