Ios Firebase-如何循环使用snapshot.hasChild（“…”）

我的数据库如下所示

users
  |
  @--uidABC
       |
       |---phone:"+13125550690"
       |
       |---followers
              |
              |----uid123
              |      |---timeStamp:111222
              |
              |----uid456
              |      |---timeStamp:777999

我使用

.observeSingleEvent

检查

uidABC

是否存在，如果存在，我想检查该路径下是否有名为

追随者的
子项

我可以使用
snapshot.hasChild（“followers”）
查看它是否可用，以及它是否如何循环遍历snapshot.hasChild（“…”）下的所有子项

我使用下面的代码，但它在错误的
快照中循环。当它应该使用
DataSnapshot
下的
followers

let ref = Database...child("users").child(uidABC)
ref.observeSingleEvent(of: .value, with: { (snapshot) in

    if !snapshot.exists() {

        // this user doesn't exist
        return
    }

    if !snapshot.hasChild("followers") {

       // this user exists but has no followers
       return
    }

    // this user exists and has followers now loop through them
    for uid in snapshot.children {

        let snapshot = uid as! DataSnapshot

        if let dict = snapshot.value as? [String:Any] {
            let timeStamp = dict["timeStamp"] as? Double
            // eg. check for a specific timeStamp
         }
     }
})

使用
子项
：

// this user exists and has followers now loop through them
for uid in snapshot.childSnapshot("followers") {

    guard let snapshot = uid as! DataSnapshot else {
     // Followers error
    }

    if let dict = snapshot.value as? [String:Any] {
        let timeStamp = dict["timeStamp"] as? Double
        // eg. check for a specific timeStamp
     }
 }

您可以在此处找到更多信息：
我从这里得到了答案

谢谢，我试过了，但是得到了一个错误-类型为'DataSnapshot'的值没有成员'child'；你是说“孩子”吗？
child
被重命名为
childSnapshot（forPath:）
谢谢你纠正我：）@LanceSamariaI我都不知道我在纠正你。我以为你正在关闭一个完全不同的快照子属性。谢谢你的帮助
let ref = Database...child("users").child(uidABC)
ref.observeSingleEvent(of: .value, with: { (snapshot) in

    if !snapshot.exists() {

        // this user doesn't exist
        return
    }

    if !snapshot.hasChild("followers") {

        // this user exists but has no followers
        return
    }

    // this user exists and has followers now loop through them
    let childSnapshot = snapshot.childSnapshot(forPath: "followers") {

    for child in childSnapshot.children {

        let snap = child as! DataSnapshot

        let uid = snap.key

        if let dict = snap.value as? [String: Any] {

            let timeStamp = dict["timeStamp"] as? Double ?? 0
            // eg. check for a specific timeStamp
        }
    }
})