异步任务在WorkManagers CallbackDispatcher中不起作用

Question

我正在使用WorkManager作为后台服务。我的代码如下

void callbackDispatcher() {
  Workmanager.executeTask((task, inputData) async {
    switch (task) {
      case "uploadLocalData":
        print("this method was called from background!");
        await BackgroundProcessHandler().uploadLocalData();
        print("background Executed!");
        return true;
       
        break;
      case Workmanager.iOSBackgroundTask:
        print("iOS background fetch delegate ran");
        return true;
        break;
    }
    return false;
   
  });
}

在executeTask中有没有等待异步方法的方法？

Answer 1

使非异步事物异步的方法是通过完成器。你创建一个完成器，等待它的未来，并在未来完成它。

Completer uploadCompleter = Completer();

void callbackDispatcher() {
  Workmanager.executeTask((task, inputData) async {
    switch (task) {
      case "uploadLocalData":
        print("this method was called from background!");
        await BackgroundProcessHandler().uploadLocalData();
        print("background Executed!");
        uploadCompleter.complete();
        return true;
       
        break;
      case Workmanager.iOSBackgroundTask:
        print("iOS background fetch delegate ran");
        return true;
        break;
    }
    return false;
   
  });
}

// somewhere else
await uploadCompleter.future;