如何在 Flutter 中一天只显示一次警告对话框？

Question

I'm working on an app in which I want to add a functionality that shows an alert dialog box only once a day when the user opens the app. I'm done with the dialog box I used the boolean variable if this bool value is true then show dialog else don't show the dialog . Once the dialog opens on tap of the button I set the bool value to false . But my question is how it will set true again at the end of the day? What should I need to do so the bool value again set to true at the end of the day?

Answer 1

Instead of using a boolean, you need the last date/time the dialog was shown.

Every time a situation occurs in which you may need to show the dialog, you get the current date/time now and compare that with date/time of the last dialog showing.

Because you can't be sure if the app will be killed or now, you also need to store the last date/time the app was shown on disk.

Answer 2

You could store the last access time of the user with Shared Preferences and check if the user was using the app today.

    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setInt('lastAccess', DateTime.now().millisecondsSinceEpoch)

    // Get last access
    final int lastAccess = prefs.getInt('lastAccess');

    if(lastAccess!=null){
      // Get last access as DateTime
      final DateTime lastAccessTime = DateTime.fromMillisecondsSinceEpoch(lastAccess);

      // Check if he opened the app
      final opened = lastAccessTime.isAfter(DateTime.now());

      if(!opened){
        // Show Dialog
      }
    }

Answer 3

I just wrote the easiest algorithm.

 SharedPreferences prefs = await SharedPreferences.getInstance();
    int? lastDay = prefs.getInt('lastDay');
    int today = DateTime.now().day;
    if (lastDay == null || lastDay != today) {
      //Show the dialog
      prefs.setInt('lastDay', today);
    }

Answer 4

timer = Timer.periodic(
 Duration(days: 1,), 
 (Timer t) => {
  //callback
 });