{
   "posts": {
      "post_1": {
         "uid": "user_1","title": "Cool Post"
      },"post_2": {
         "uid": "user_1","title": "Another Cool Post"
      },"post_3": {
         "uid": "user_2","title": "My Cool Post"
      }
   },"postLikes": {
      "user_1": {
         "post_3": true
      },"user_2": {
         "post_1": true,"post_2": true         
      }
   }
}

位置/帖子检索所有帖子.
location / postLikes检索帖子上的所有喜欢.

所以,假设您是user_1.要获取user_1喜欢的帖子,您可以编写此Firebase数据库侦听器：

let ref = Firebase(url: "<my-firebase-app>")
let uid = "user_1"
let userRef = ref.childByAppendingPath(uid)
userRef.observeEventType(.Value) { (snap: FDataSnapshot!) in
  print(snap.value) // prints all of the likes

  // loop through each like
  for child in snap.children {
    let childSnap = child as! FDataSnapshot
    print(childSnap.value) // print a single like
  }
}

这里需要注意的重要一点是数据结构的“平坦性”. postLikes不存储在每个帖子下.这意味着您可以在不获取所有喜欢的情况下检索帖子.但是,如果你想同时获得两者,你仍然可以这样做,因为你知道用户的id.

Try giving the Firebase guide on Structuring Data a read through