Question

我有下面的代码是可选的。

"\(postArray[indexPath.row].user.username)"

当我打印值时，我得到类似以下内容：可选（“ helloman”）但是当我强制拆开以摆脱Optional（）时，应用程序崩溃了零。 为什么会这样？我该如何解决？

我打印：

    print(postArray[indexPath.row].user.username, " loop full\(indexPath.row)")
    print(postArray[indexPath.row].user.username!, " loop full\(indexPath.row)")

并获得以下结果

nil  loop full2

//在此处崩溃

我将用户添加到每个帖子对象中，如下所示：

    func retrieveUsersInfo(userObj: User) {

    let ref = Database.database().reference()

    if userObj.userID != nil {
        print("inside if of retrieveUsers")

        let UID = userObj.userID!
        print(UID, "<-- uid promg")
        let currentUID = "\(UID)"
        print(currentUID, "<<- current uid")
        print(lastUID, "<-- chhhc")

        if lastUID == nil {
            print("last uid 6was nil")
            ref.child("users2").child(UID).observe(.value, with: { (snapshot) in
                print(snapshot.childSnapshot(forPath: "username").value as! String, "0302310320101320312032101")

                print("here?")
                do {
                    self.addUserDataToObject(userObj: userObj, snapshot: snapshot)
                }

            })

        } else if currentUID == lastUID! {
            print("hello?")
            ref.child("users2").child(UID).observe(.value, with: { (snapshot) in
                print(snapshot.childSnapshot(forPath: "username").value as! String, "0302310320101320312032101")

                do {
                    self.addUserDataToObject(userObj: userObj, snapshot: snapshot)
                }

            })
        } else if currentUID != lastUID! {
            print("vai malandra") //the stuff below should be made into another function to reduce text; be more fficient
            ref.child("users2").child(UID).observe(.value, with: { (snapshot) in
                print(snapshot.childSnapshot(forPath: "username").value as! String, "0302310320101320312032101")

                do {
                    self.addUserDataToObject(userObj: userObj, snapshot: snapshot)
                }

            })

        } else {
            print("gggg")
        }
        lastUID = "\(UID)"
    }
}

使用白粉功能：

    func addUserDataToObject(userObj: User, snapshot: DataSnapshot) {
    if "\(snapshot.childSnapshot(forPath: "username").value as! String)" != nil {
        userObj.fullName = "\(snapshot.childSnapshot(forPath: "fullName").value as! String)"
        userObj.username = "\(snapshot.childSnapshot(forPath: "username").value as! String)"
        userObj.profileImageUrl = "\(snapshot.childSnapshot(forPath: "profileImage").value as! String)"
    } else {
        print("the username was nil!")
    }
}

对于我从.childAdded中获得的每个用户（从下面的用户列表中获得），我都调用此方法

可选（[值]）！产生nil（错误），尽管它具有值

0 个答案: