我試圖在應用程式恢復時更新這兩個變數，變數是分鐘和小時。現在，當我恢復應用程式時，值不會更新。
@override
void initState() {
super.initState();
WidgetsBinding.instance!.addObserver(this);
dateTimeNow = DateTime.parse('${prefs.getString('startTime')}');
startedDateTime = DateTime.now();
minutes = startedDateTime.difference(dateTimeNow).inMinutes % 60;
hours = startedDateTime.difference(dateTimeNow).inHours;
if (minutes < 0) {
minutes = 0;
}
}
@override
void didChangeAppLifecycleState(AppLifecycleState state) {
switch (state) {
case AppLifecycleState.inactive:
print("Inactive");
break;
case AppLifecycleState.paused:
print("Paused");
break;
case AppLifecycleState.resumed:
print('resumed');
setState(() { // trying to updated
minutes = startedDateTime.difference(dateTimeNow).inMinutes % 60;
hours = startedDateTime.difference(dateTimeNow).inHours;
});
break;
}
}
uj5u.com熱心網友回復：
您似乎沒有更新該startedDateTime值。您僅在狀態的第一次初始化期間設定它，但稍后您不會更新該值。這意味著，即使在使用 更新您的值之后didChangeAppLifecycleState， thestartedDateTime仍然是相同的，因此minutesorhours值保持不變。
嘗試做這樣的事情：
@override
void didChangeAppLifecycleState(AppLifecycleState state) {
super.didChangeAppLifecycleState(state); // <-- Add this as well
switch (state) {
<...>
case AppLifecycleState.resumed:
print('resumed');
setState(() {
// trying to updated
startedDateTime = DateTime.now(); // <-- Update the value
minutes = startedDateTime.difference(dateTimeNow).inMinutes % 60;
hours = startedDateTime.difference(dateTimeNow).inHours;
});
break;
}
}
uj5u.com熱心網友回復：
請在方法super.didChangeAppLifecycleState(state);末尾添加didChangeAppLifecycleState()如下：
void didChangeAppLifecycleState(AppLifecycleState state) {
switch (state) {
case AppLifecycleState.inactive:
print("Inactive");
break;
case AppLifecycleState.paused:
print("Paused");
break;
case AppLifecycleState.resumed:
print('resumed');
setState(() { // trying to updated
minutes = startedDateTime.difference(dateTimeNow).inMinutes % 60;
hours = startedDateTime.difference(dateTimeNow).inHours;
});
break;
}
super.didChangeAppLifecycleState(state);
}
并覆寫 dispose 方法：
void dispose() {
WidgetsBinding.instance!.removeObserver(this);
super.dispose();
}
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