关于IOS应用的推送服务的 topic 参数 怎么获得？

[SolidCocoi]

最近在尝试 用 Java 的 pushy 写ios 推送后端服务，苹果网关那边总给我返回

Notification rejected by the APNs gateway: TopicDisallowed

苹果官网给的请求样例是这样，但是我试了很多次 还是没搞明白 <MyAppTopic> 这个参数是个啥，求大大指点

HEADERS
  - END_STREAM
  + END_HEADERS
  :method = POST
  :scheme = https
  :path = /3/device/00fc13adff785122b4ad28809a3420982341241421348097878e577c991de8f0
  host = api.development.push.apple.com
  apns-id = eabeae54-14a8-11e5-b60b-1697f925ec7b
  apns-expiration = 0
  apns-priority = 10
  apns-topic = <MyAppTopic> 
DATA
  + END_STREAM
    { "aps" : { "alert" : "Hello" } }