queryEqualTo被跳过

Question

i'm trying to set up a viewCount for my app, when I set the breakpoints up and go through the code it always skips past the queryOrdered and i'm not exactly sure why

func increaseViewCount(username: String, time: NSNumber){
    guard let uid = Auth.auth().currentUser?.uid else{
        return
    }
    let refOfUserName = Database.database().reference().child("Users").child(uid)
    refOfUserName.observeSingleEvent(of: .value, with: {(snapshot) in
        let dictionaryOfUser = snapshot.value as? [String: AnyObject]
       // let currentUsersName = dictionaryOfUser?["username"] as? String
    let currentUsersName = "hello"

        if username == currentUsersName {
            print("this is the same user")

        }else{

            let postRef = Database.database().reference().child("HistoryOfPosts").child("post")
            postRef.queryOrdered(byChild: "post").queryEqual(toValue: time).observeSingleEvent(of: .childAdded, with: {(snapshotPost) in

                print(snapshotPost.exists())
                print(snapshotPost)

                let valString = snapshotPost.value
                let number = valString as! NSNumber
                var value = number.intValue
                value = value + 1
                let values = ["viewCount": value] as [String:Any]
                postRef.updateChildValues(values)

            })
        }
    })
}

Answer 1

The data is loaded from the Firebase Database asynchronously. Instead of waiting for that loading to complete, the program continues with the statement after you attach the observer.

In this case that means that the code pretty much exits increaseViewCount() straight after it attaches the observer. Then once the data comes back from the Firebase servers, the code in your callback block is executed.

To get into the callback block, place a breakpoint on the first statement in that block.