我设法解决这个问题得益于这个答案： https://***.com/a/37550067/516338

I managed to fix the problem thanks to this answer: https://***.com/a/37550067/516338

基本上，尽管不在文档中，但您必须在iOS上将priority字段设置为high，如下所示：

Basically, although NOT in the documents, you have to set the "priority" field to "high" on iOS, like this:

{   
  "to": "cHPpZ_s14EA:APA91bG56znW...",
  "priority": "high",
  "notification" : {
    "body" : "hello!",
    "title": "afruz",
    "sound": "default"
  }
}