键盘上方增加确认按钮，点击验证拼写

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

LearnEnglish/LearnEnglish/Views/SpellingInputView.swift

@@ -2,6 +2,7 @@ import UIKit
 
 final class SpellingInputView: UIView, UITextFieldDelegate {
     var onChange: (() -> Void)?
+    var onSubmit: (() -> Void)?
 
     private let hiddenField = UITextField()
     private let stack = UIStackView()
@@ -56,6 +57,23 @@ final class SpellingInputView: UIView, UITextFieldDelegate {
         hiddenField.frame = .zero
         addSubview(hiddenField)
 
+        let accessory = UIView()
+        accessory.frame = CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: 52)
+        accessory.backgroundColor = .clear
+        let confirmButton = UIButton(type: .system)
+        confirmButton.setTitle("确认", for: .normal)
+        confirmButton.titleLabel?.font = .systemFont(ofSize: 17, weight: .semibold)
+        confirmButton.addAction(UIAction { [weak self] _ in
+            self?.onSubmit?()
+        }, for: .touchUpInside)
+        confirmButton.translatesAutoresizingMaskIntoConstraints = false
+        accessory.addSubview(confirmButton)
+        NSLayoutConstraint.activate([
+            confirmButton.trailingAnchor.constraint(equalTo: accessory.trailingAnchor, constant: -8),
+            confirmButton.topAnchor.constraint(equalTo: accessory.topAnchor, constant: 8)
+        ])
+        hiddenField.inputAccessoryView = accessory
+
         addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(reactivate)))
     }