vsync property Null safety

TickerProvider? vsync

A TickerProvider to use when animating the scroll position.

Implementation

TickerProvider? get vsync => _vsync;
void vsync=(TickerProvider? value)

Implementation

set vsync(TickerProvider? value) {
  if (value == _vsync)
    return;
  _vsync = value;
  if (value == null) {
    _controller?.dispose();
    _controller = null;
  } else {
    _controller?.resync(value);
  }
}