recognizer property

GestureRecognizer recognizer
final

A gesture recognizer that will receive events that hit this text span.

TextSpan itself does not implement hit testing or event dispatch. The object that manages the TextSpan painting is also responsible for dispatching events. In the rendering library, that is the RenderParagraph object, which corresponds to the RichText widget in the widgets layer; these objects do not bubble events in TextSpans, so a recognizer is only effective for events that directly hit the text of that TextSpan, not any of its children.

TextSpan also does not manage the lifetime of the gesture recognizer. The code that owns the GestureRecognizer object must call GestureRecognizer.dispose when the TextSpan object is no longer used.

This example shows how to manage the lifetime of a gesture recognizer provided to a TextSpan object. It defines a BuzzingText widget which uses the HapticFeedback class to vibrate the device when the user long-presses the "find the" span, which is underlined in wavy green. The hit-testing is handled by the RichText widget. 
class BuzzingText extends StatefulWidget {
  @override
  _BuzzingTextState createState() => _BuzzingTextState();
}

class _BuzzingTextState extends State<BuzzingText> {
  LongPressGestureRecognizer _longPressRecognizer;

  @override
  void initState() {
    super.initState();
    _longPressRecognizer = LongPressGestureRecognizer()
      ..onLongPress = _handlePress;
  }

  @override
  void dispose() {
    _longPressRecognizer.dispose();
    super.dispose();
  }

  void _handlePress() {
    HapticFeedback.vibrate();
  }

  @override
  Widget build(BuildContext context) {
    return RichText(
      text: TextSpan(
        text: 'Can you ',
        style: TextStyle(color: Colors.black),
        children: <TextSpan>[
          TextSpan(
            text: 'find the',
            style: TextStyle(
              color: Colors.green,
              decoration: TextDecoration.underline,
              decorationStyle: TextDecorationStyle.wavy,
            ),
            recognizer: _longPressRecognizer,
          ),
          TextSpan(
            text: ' secret?',
          ),
        ],
      ),
    );
  }
}

Implementation 

final GestureRecognizer recognizer