How to save max duration with sharedpref in flutter? - flutter

Question

I tried to save duration with sharedpreference only if my last duration is superior to the current duration and so show the MAX duration. my problem is that I don't know how to compare two string duration.
here is the code thanks (#ZeRj)
load_lastPressString()async{
SharedPreferences prefs = await SharedPreferences.getInstance();
setState(() {
final lastPressString = prefs.getString("lastButtonPress");
_lastButtonPress = lastPressString!=null ? DateTime.parse(lastPressString) : DateTime.now();
_updateTimer();
_ticker = Timer.periodic(Duration(seconds:1),(_)=>_updateTimer());
});
}
save_lastPressString()async{
SharedPreferences prefs = await SharedPreferences.getInstance();
setState(() {
prefs.setString('_lastButtonPress', _lastButtonPress.toIso8601String());
});
}
void _updateTimer() {
final duration = DateTime.now().difference(_lastButtonPress);
final newDuration = _formatDuration(duration);
setState(() {
_pressDuration = newDuration;
});
}
String _formatDuration(Duration duration) {
String twoDigits(int n) {
if (n >= 10) return "$n";
return "0$n";
}
String twoDigitMinutes = twoDigits(duration.inMinutes.remainder(60));
String twoDigitSeconds = twoDigits(duration.inSeconds.remainder(60));
return "${twoDigits(duration.inDays)}:${twoDigits(duration.inHours)}:$twoDigitMinutes:$twoDigitSeconds";
}
I tried the code bellow, but I can't use > with string and tried to parse int but not possible with date, and I tried to extract each decimal with regex but it's to complicated and I have errors I havn't understand.
save_max_lastPress()async{
SharedPreferences prefs = await SharedPreferences.getInstance();
setState(() {
if(_lastButtonPress>Max_lastButtonPress)
{
prefs.setString('_max_lastPress', Max_lastButtonPress) ;
}
}
);
}

Answer 1

For that you have to save the maximal as the duration.
Use prefs.setInt("maxDuration",maxDuration.toSeconds()) to save it as a int in shared preferences and load it with
Duration(seconds: prefs.getInt("maxDuration")
You can simply compare two instances of Duration.
I edited the last example to implement this feature:
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutterfly/SharedPrefs.dart';
import 'package:flutterfly/SharedPrefs.dart' as prefix0;
class TestWidget extends StatefulWidget {
#override
_TestWidgetState createState() => _TestWidgetState();
}
class _TestWidgetState extends State<TestWidget> {
DateTime _lastButtonPress;
String _pressDuration;
Timer _ticker;
Duration _maxDuration;
#override
Widget build(BuildContext context) {
return Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text("Time since button pressed"),
Text(_pressDuration),
Text("Maximal Duration"),
Text(_formatDuration(_maxDuration)),
RaisedButton(
child: Text("Press me"),
onPressed: () {
_lastButtonPress = DateTime.now();
_updateTimer();
sharedPreferences.setString("lastButtonPress",_lastButtonPress.toIso8601String());
},
)
],
),
);
}
#override
void initState() {
super.initState();
//load max duration, if there is none start with 0
_maxDuration = Duration(seconds:sharedPreferences.getInt("maxDuration")??0);
final lastPressString = sharedPreferences.getString("lastButtonPress");
_lastButtonPress = lastPressString!=null ? DateTime.parse(lastPressString) : DateTime.now();
_updateTimer();
_ticker = Timer.periodic(Duration(seconds:1),(_)=>_updateTimer());
}
#override
void dispose() {
_ticker.cancel();
super.dispose();
}
void _updateTimer() {
final duration = DateTime.now().difference(_lastButtonPress);
//check for new max duration here
Duration newMaxDuration = _maxDuration;
if(duration> _maxDuration) {
//save when current duration is a new max
newMaxDuration = duration;
sharedPreferences.setInt("maxDuration",newMaxDuration.inSeconds);
}
final newDuration =_formatDuration(duration);
setState(() {
_maxDuration = newMaxDuration;
_pressDuration = newDuration;
});
}
String _formatDuration(Duration duration) {
String twoDigits(int n) {
if (n >= 10) return "$n";
return "0$n";
}
String twoDigitMinutes = twoDigits(duration.inMinutes.remainder(60));
String twoDigitSeconds = twoDigits(duration.inSeconds.remainder(60));
return "${twoDigits(duration.inHours)}:$twoDigitMinutes:$twoDigitSeconds";
}
}