delay method
延迟处理 @params milliSeconds 延迟多少毫秒执行
Implementation
StreamSubscription delay(int milliSeconds, ValueChanged<T> listen) {
final stream = Stream.fromFuture(Future.delayed(milliSeconds.toMilliSeconds)).listen((event) {
if (mounted) {
listen(event);
}
});
addStreamSubscription(stream);
return stream;
}