Flutter_beacon 插件在 IOS 的后台不工作

Question

Is there any workaround here to keep MainActivity/App alive in the background in the IOS.

As I am using 2 different plugins to scan and broadcast at the same time.

here's my scanning code: I am using FLUTTER_BEACON plugin

_streamRanging =
        flutterBeacon.ranging(regions).listen((RangingResult result) {
      print(result);
      if (result != null && mounted) {
        setState(() {
          _regionBeacons[result.region] = result.beacons;
          _beacons.clear();
          _regionBeacons.values.forEach((list) {
            _beacons.addAll(list);
          });
          _beacons.sort(_compareParameters);
        });
      }
    });

Answer 1

While this question is specifically about Flutter, iOS enforces certain rules on an app's background uses regardless of how an app is built:

1. When an iOS app is not visible on the screen, it is considered in the background.

2. When in the background, an app's beacon ranging is blocked unless:

   a. The app sets up a background process (which will enable ONLY 30 seconds of ranging on iOS 13+ each time the app is put to the background) Read more here

   b. The sets up a background process, declares "location" background mode, and requests periodic location updates. This will unlock unlimited background ranging, but it may make it impossible to get approved for the app store unless you can justify an obvious user-facing background location benefit.

   c. As an alternative to (b) if the app does beacon monitoring, if a beacon monitoring region entry or exit can be triggered periodically, it will unlock an extra 30 seconds of background ranging as described in (a). This is possible to do if you can deploy an alternating beacon in the location where the app is used.

The workarounds described in (2) are the same whether you use Flutter or not. The specifics of how you implement a background task is certainly different with Flutter.

Edit 4/11/2020: Apple announced plans for a new beacon advertisement that will work in the background. See here for more info.