How can I use showDialog with await - async-await

Question

I have three examples of showDialog. I presume that _showAlert1 is correct, however it uses 2 functions to achieve it. _showAlert2 also works, however I presume it is not correct because I believe that showDialog is async, and I presume that this function relies on the dialog being displayed in sufficient time. _showAlert3 does not work because the dialog stays on the screen and does not clear.
If _showAlert2 although it works is incorrect for the above reason, could someone please show me how this should be structured so that this can be done in one function.
Examples:
void _showAlert0(BuildContext context, String text, int seconds) async {
return await showDialog(
barrierDismissible: false,
context: context,
builder: (context) => AlertDialog(
title: Text("Error"),
content: Text(text),
));
}
void _showAlert1(BuildContext context, String text, int seconds) async {
_showAlert0(context, text, seconds);
await Future.delayed(Duration(seconds: seconds));
Navigator.of(context).pop(true);
}
void _showAlert2(BuildContext context, String text, int seconds) async {
showDialog(
barrierDismissible: false,
context: context,
builder: (context) => AlertDialog(
title: Text("Error"),
content: Text(text),
));
await Future.delayed(Duration(seconds: seconds));
Navigator.of(context).pop(true);
}
void _showAlert3(BuildContext context, String text, int seconds) async {
await showDialog(
barrierDismissible: false,
context: context,
builder: (context) => AlertDialog(
title: Text("Error"),
content: Text(text),
));
await Future.delayed(Duration(seconds: seconds));
Navigator.of(context).pop(true);
}

Answer 1

Not sure if there is a better way, but the following appears to work. Note the "then" clause on the call to showDialog().
void _showAlert3(BuildContext context, String text, int seconds) async {
showDialog(
barrierDismissible: false,
context: context,
builder: (context) => AlertDialog(
title: Text("Error"),
content: Text(text),
)).then((val) {});
await Future.delayed(Duration(seconds: seconds));
Navigator.of(context).pop(true);
}
As for trolls, RTFQ ("structured so that this can be done in one function") and if you don't want to help then go away.