Adding items to Firebase array in Swift without observing for array first

问题

Currently I add a new post to my Firebase array by observing for the array first, appending my new post, and then updating the ref:

REF_USER.child(UID).observeSingleEventOfType(.Value, withBlock: { snapshot in
   if !snapshot.exists() {return}
   if let dict = snapshot.value as? Dictionary<String, AnyObject>, 
      let posts = dict["posts" as? [String] {
      posts.append(newPost)
      REF_USER.child(UID + "/posts").setValue(posts)
   }
}

Is there a way to skip the step of observing, and straight away update posts in an array? Hypothetically, something like:

REF_USER.child(UID + "/posts").addToArray(newPost)

回答1:

It's generally good practice to avoid array's in Firebase as they are super hard to deal with; the individual elements cannot be accessed directly and they cannot be updated - they have to be re-written.

Not sure why you are going through the steps outlined in your question to add a new post but here's another solution:

thisPostRef = postsRef.childByAutoId //create a new post node
thisPostRef.setValue("here's a new post") //store the post in it

Edit:

This will result in a structure like this

posts
  post_id_0: "here's a new post"
  post_id_1: "another post"
  post_id_2: "cool post"

This structure avoids the pitfalls of arrays.

Another edit. The OP asks how to write it to the users/UID/posts node

usersRef = rootRef.childByAppendingPath("users")
thisUserRef = usersRef.childByAppendingPath(the users uid)
thisUserPostRef = thisUserRef.childByAutoId //create a new post node
thisUserPostRef.setValue("here's a new post") //store the post in it

来源：https://stackoverflow.com/questions/37435638/adding-items-to-firebase-array-in-swift-without-observing-for-array-first