[ios17][text_input]fix chinese language switch freeze, and missing auto correction menu in iOS 17

shell/platform/darwin/ios/framework/Source/FlutterTextInputPlugin.mm

@@ -619,6 +619,20 @@ - (UITextRange*)rangeEnclosingPosition:(UITextPosition*)position
 }
 
 - (UITextRange*)lineEnclosingPosition:(UITextPosition*)position {
+  // TODO(hellohuanlin): Remove iOS 17 check. The same logic should apply to older versions too.
+  if (@available(iOS 17.0, *)) {
+    FlutterTextPosition* flutterPosition = (FlutterTextPosition*)position;
+    if (flutterPosition.index > _textInputView.text.length) {
+      return nil;
+    }
+    // end of document with forward affinity is still considered as part of the document, which is
+    // used by voice control's delete line command.
+    if (flutterPosition.index == _textInputView.text.length &&
+        flutterPosition.affinity == UITextStorageDirectionBackward) {
+      return nil;
+    }
+  }
+
   // Gets the first line break position after the input position.
   NSString* textAfter = [_textInputView
       textInRange:[_textInputView textRangeFromPosition:position

shell/platform/darwin/ios/framework/Source/FlutterTextInputPluginTest.mm

@@ -2660,6 +2660,47 @@ - (void)testFlutterTokenizerCanParseLines {
   XCTAssertEqual(range.range.length, 20u);
 }
 
+- (void)testFlutterTokenizerLineRangeQueryWithEndOfDocumentAndBackwardAffinity {
+  FlutterTextInputView* inputView = [[FlutterTextInputView alloc] initWithOwner:textInputPlugin];
+  id<UITextInputTokenizer> tokenizer = [inputView tokenizer];
+
+  NSString* text = @"Random text\nwith 2 lines";
+  [inputView insertText:text];
+
+  FlutterTextPosition* endOfDocumentWithBackwardAffinity =
+      [FlutterTextPosition positionWithIndex:text.length affinity:UITextStorageDirectionBackward];
+
+  FlutterTextRange* range =
+      (FlutterTextRange*)[tokenizer rangeEnclosingPosition:endOfDocumentWithBackwardAffinity
+                                           withGranularity:UITextGranularityLine
+                                               inDirection:UITextLayoutDirectionRight];
+
+  if (@available(iOS 17.0, *)) {
+    XCTAssertNil(range);
+  } else {
+    XCTAssertEqual(range.range.location, 12u);
+    XCTAssertEqual(range.range.length, 12u);
+  }
+}
+
+- (void)testFlutterTokenizerLineRangeQueryWithEndOfDocumentAndForwardAffinity {
+  FlutterTextInputView* inputView = [[FlutterTextInputView alloc] initWithOwner:textInputPlugin];
+  id<UITextInputTokenizer> tokenizer = [inputView tokenizer];
+
+  NSString* text = @"Random text\nwith 2 lines";
+  [inputView insertText:text];
+
+  FlutterTextPosition* endOfDocumentWithForwardAffinity =
+      [FlutterTextPosition positionWithIndex:text.length affinity:UITextStorageDirectionForward];
+
+  range = (FlutterTextRange*)[tokenizer rangeEnclosingPosition:endOfDocumentWithForwardAffinity
+                                               withGranularity:UITextGranularityLine
+                                                   inDirection:UITextLayoutDirectionRight];
+
+  XCTAssertEqual(range.range.location, 12u);
+  XCTAssertEqual(range.range.length, 12u);
+}
+
 - (void)testFlutterTextInputPluginRetainsFlutterTextInputView {
   FlutterViewController* flutterViewController = [[FlutterViewController alloc] init];
   FlutterTextInputPlugin* myInputPlugin = [[FlutterTextInputPlugin alloc] initWithDelegate:engine];