格式化操作增加空内容拦截和 Alert 提示

Note/FormatNoteViewController.swift

@@ -102,6 +102,16 @@ class FormatNoteViewController: UIViewController {
         }
     }
 
+    private func trimmedText() -> String {
+        return textView.text?.trimmingCharacters(in: .whitespacesAndNewlines) ?? ""
+    }
+
+    private func showEmptyAlert() {
+        let alert = UIAlertController(title: "提示", message: "请输入内容后再进行格式化", preferredStyle: .alert)
+        alert.addAction(UIAlertAction(title: "确定", style: .default))
+        present(alert, animated: true)
+    }
+
     @objc private func didTapResetButton() {
         textView.text = ""
         rightBarButtonMode = .paste
@@ -124,6 +134,10 @@ class FormatNoteViewController: UIViewController {
     }
 
     @objc private func didTapiCloudButton() {
+        guard !trimmedText().isEmpty else {
+            showEmptyAlert()
+            return
+        }
         if isCloudFormatted {
             saveToFiles()
         } else {
@@ -136,6 +150,10 @@ class FormatNoteViewController: UIViewController {
     }
 
     @objc private func didTapNoteButton() {
+        guard !trimmedText().isEmpty else {
+            showEmptyAlert()
+            return
+        }
         textView.text = formatForNote(textView.text)
         rightBarButtonMode = .reset
         updateRightBarButtonItem()