CoreData: fetching and uploading data to server

I have a scheduled function uses a private queue context to fetch objects from CoreData and uploads them to a server and deletes the fetched objects if successfully uploaded. The upload function is an async function that uses URLSession.

context.perform {
   do {
      let fetchRequest = NSFetchRequest<CustomEntity>
      fetchRequest = CustomEntity.fetchRequest()
   
      let objects = try context.fetch(fetchRequest)
      let data = JSONSerialization.data(withJsonObject: objects, options: [])
      
      //
      await uploadToServer(data)

      // delete after successful upload:
      objects.forEach(context.delete)
      try context.save()

      } catch let error {
   }
}

However, this doesn't seem legal though. xcode gives me an error: 'async' call in a function that does not support concurrency.

Stuck on how to invoke the async function within the context.perform { } block