add comments and readme introductions

README.md

@@ -1,6 +1,6 @@
 # renamer
 
-<img alt="Get it on Google Play" src="https://raw.githubusercontent.com/sun-jiao/renamer/main/assets/desktop.png" height=100px /> 
+<img alt="renamer app icon" src="https://raw.githubusercontent.com/sun-jiao/renamer/main/assets/desktop.png" height=100px /> 
 
 A bulk file renamer written in flutter (dart).
 
@@ -11,7 +11,7 @@ todo:
 - ~~Convert, including case convert, Chinese simp/trad/pinyin convert, Latin/Cyrillic script transliteration~~.(Done.)
 - ~~Incremental renaming: for example, RenamerFile-1, RenamerFile-2, RenamerFile-3, RenamerFile-4, ...~~.(Done.)
 - Rules re-editing.
-- Implement iOS renamer with specific code and Platform channel, references: [Writing custom platform-specific code](https://docs.flutter.dev/platform-integration/platform-channels?tab=type-mappings-swift-tab#type-mappings-swift-tab), [Providing access to directories](https://developer.apple.com/documentation/uikit/view_controllers/providing_access_to_directories), [juanmartin/renamerApp-ios](https://github.com/juanmartin/renamerApp-ios)
+- ~~Implement iOS renamer with specific code and Platform channel~~.(Done.) In fact, I have no Apple development experience at all, and I don’t even know the Swift language. The iOS and macOS native code was completed with the following links as references: [Writing custom platform-specific code](https://docs.flutter.dev/platform-integration/platform-channels?tab=type-mappings-swift-tab#type-mappings-swift-tab), [Providing access to directories](https://developer.apple.com/documentation/uikit/view_controllers/providing_access_to_directories), [juanmartin/renamerApp-ios](https://github.com/juanmartin/renamerApp-ios). Therefore, if there are any errors in the swift code, please fell free to point them out by opening an issue or a pull request. I'll be very grateful to you.
 
 # Screenshots
 ## Desktop

lib/main.dart

@@ -49,7 +49,7 @@ class RenamerApp extends StatelessWidget {
       locale: _appLocale,
       debugShowCheckedModeBanner: false,
       theme: ThemeData(
-        fontFamily: Platform.isWindows ? "微软雅黑" : null,
+        fontFamily: Platform.isWindows ? "微软雅黑" : null, // fixed Chinese font rendering error
         colorScheme: ColorScheme.fromSeed(
           brightness: Brightness.light,
           seedColor: const Color(0xff9cdce8),
@@ -64,7 +64,7 @@ class RenamerApp extends StatelessWidget {
         ],
       ),
       darkTheme: ThemeData(
-        fontFamily: Platform.isWindows ? "微软雅黑" : null,
+        fontFamily: Platform.isWindows ? "微软雅黑" : null, // fixed Chinese font rendering error
         colorScheme: ColorScheme.fromSeed(
           brightness: Brightness.dark,
           seedColor: const Color(0xff26546e),