Support non-ASCII characters for writing

Author: Voklen

docs/Usage/Storage Access Framework.md

@@ -253,7 +253,7 @@ final DocumentFile? createdFile = createFileAsBytes(
   parentUri,
   mimeType: 'text/plain',
   displayName: 'Sample File Name',
-  bytes: Uint8List.fromList(fileContent.codeUnits),
+  bytes: Uint8List.fromList(utf8.encode(fileContent)),
 );
 ```
 
@@ -272,14 +272,14 @@ final String fileContent = 'My File Content';
 /// Write to a file using a [Uint8List] as file contents [bytes]
 final bool? success = writeToFileAsBytes(
   documentUri,
-  bytes: Uint8List.fromList(fileContent.codeUnits),
+  bytes: Uint8List.fromList(utf8.encode(fileContent)),
   mode: FileMode.write,
 );
 
 /// Append to a file using a [Uint8List] as file contents [bytes]
 final bool? success = writeToFileAsBytes(
   documentUri,
-  bytes: Uint8List.fromList(fileContent.codeUnits),
+  bytes: Uint8List.fromList(utf8.encode(fileContent)),
   mode: FileMode.write,
 );
 ```
@@ -602,7 +602,7 @@ final DocumentFile? createdFile = createFile(
   parentUri,
   mimeType: 'text/plain',
   displayName: 'Sample File Name',
-  content: Uint8List.fromList(fileContent.codeUnits),
+  content: Uint8List.fromList(utf8.encode(fileContent)),
 );
 ```
 
@@ -637,14 +637,14 @@ final bool? success = writeToFile(
 /// Write to a file using a [Uint8List] as file contents [bytes]
 final bool? success = writeToFile(
   documentUri,
-  content: Uint8List.fromList(fileContent.codeUnits),
+  content: Uint8List.fromList(utf8.encode(fileContent)),
   mode: FileMode.write,
 );
 
 /// Append to a file using a [Uint8List] as file contents [bytes]
 final bool? success = writeToFile(
   documentUri,
-  content: Uint8List.fromList(fileContent.codeUnits),
+  content: Uint8List.fromList(utf8.encode(fileContent)),
   mode: FileMode.append,
 );
 ```

lib/src/saf/saf.dart

@@ -313,7 +313,7 @@ Future<DocumentFile?> createFileAsString(
     parentUri,
     displayName: displayName,
     mimeType: mimeType,
-    bytes: Uint8List.fromList(content.codeUnits),
+    bytes: Uint8List.fromList(utf8.encode(content)),
   );
 }
 
@@ -385,7 +385,7 @@ Future<bool?> writeToFileAsString(
 }) {
   return writeToFileAsBytes(
     uri,
-    bytes: Uint8List.fromList(content.codeUnits),
+    bytes: Uint8List.fromList(utf8.encode(content)),
     mode: mode,
   );
 }