大小写切换按钮移至导航栏右侧

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

LearnEnglish/LearnEnglish/Views/QuizViewController.swift

@@ -36,6 +36,10 @@ final class QuizViewController: UIViewController {
         target: nil,
         action: nil
     )
+    private lazy var caseToggleItem = UIBarButtonItem(
+        image: UIImage(systemName: "textformat"),
+        style: .plain, target: self, action: #selector(toggleCase)
+    )
 
     private var current: QuizQuestion? {
         questions.indices.contains(currentIndex) ? questions[currentIndex] : nil
@@ -68,10 +72,6 @@ final class QuizViewController: UIViewController {
         view.backgroundColor = .systemBackground
         title = config.mode.rawValue
         navigationItem.largeTitleDisplayMode = .never
-        navigationItem.leftBarButtonItem = UIBarButtonItem(
-            image: UIImage(systemName: "textformat"),
-            style: .plain, target: self, action: #selector(toggleCase))
-        updateCaseButton()
         buildLayout()
         showQuestion()
     }
@@ -200,7 +200,14 @@ final class QuizViewController: UIViewController {
         resultLabel.isHidden = true
         resultPhoneticLabel.isHidden = true
 
-        navigationItem.rightBarButtonItem = config.mode == .zhToEn ? nil : navSpeakerItem
+        if config.mode == .spelling {
+            updateCaseButton()
+            navigationItem.rightBarButtonItems = [navSpeakerItem, caseToggleItem]
+        } else if config.mode == .zhToEn {
+            navigationItem.rightBarButtonItems = nil
+        } else {
+            navigationItem.rightBarButtonItem = navSpeakerItem
+        }
 
         let isSpelling = config.mode == .spelling
         let isDictation = config.mode == .dictation
@@ -411,7 +418,7 @@ final class QuizViewController: UIViewController {
     }
 
     private func updateCaseButton() {
-        navigationItem.leftBarButtonItem?.tintColor = isUppercase ? Theme.Color.accent : .tertiaryLabel
+        caseToggleItem.tintColor = isUppercase ? Theme.Color.accent : .tertiaryLabel
     }
 
     @objc private func speakCurrentWord() {