Question

我无法将postid发送到注释vc，以便可以将其保存在Firebase中。

我正在关注在线教程，我们在Firebase上构建this体系结构，但是当我将数据发送到Firebase时，它并没有捕获this screenshot上的postId。我显然缺少了一些东西。如果有人可以阐明我的错误可能会很感激。下面，我将在“注释视图控制器”功能中将数据发送到Firebase。

  @IBAction func sendButtonPressed(_ sender: UIButton) {

    let ref = Database.database().reference()
    let commentsReference = ref.child("comments")
    let newCommentId = commentsReference.childByAutoId().key
    let newCommentReference = commentsReference.child(newCommentId)

    //current user information
    guard let currentUser = Auth.auth().currentUser else {
        return
    }

    let currentUserId = currentUser.uid
    newCommentReference.setValue(["userid": currentUserId, "commentText": commentTextField.text!]) { (error, ref) in

        if error != nil {
            ProgressHUD.showError(error!.localizedDescription)
            return
            }
        let postCommentRef = Database.database().reference().child("post-comments").child(self.postIdNew).child(newCommentId)
        postCommentRef.setValue(true, withCompletionBlock: { (error, ref) in
            if error != nil {
                ProgressHUD.showError(error!.localizedDescription)
                return
            }
        })
        self.empty()
        self.view.endEditing(true)
    }
}

这就是我应该从Home View Controller中获取postId引用的方式。

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "commentSegue" {
        let commentVC = segue.destination as! CommentViewController
        let postId = sender as! String
        commentVC.postIdNew = postId
    }
}

这是我的收藏夹视图扩展

extension HomeViewController: UICollectionViewDelegate, UICollectionViewDataSource {

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

    if collectionView == self.lostCollectionView {

        return posts.count
    }

    if collectionView == self.foundCollectionView {

        return newPostsFound.count

    }

    if collectionView == self.adoptionCollectionView {

        return postsadoption.count
    }

    else {

        return 0
    }

}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    switch collectionView {

    case lostCollectionView:

        let lostcell: LostCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "Lostcell", for: indexPath) as! LostCollectionViewCell

        let post = posts[indexPath.row]
        let user = users[indexPath.row]
        lostcell.post = post
        lostcell.user = user

        //Make TextView Clickable
        lostcell.phoneLostTextView.isEditable = false;
        lostcell.phoneLostTextView.dataDetectorTypes = UIDataDetectorTypes.phoneNumber

        //Make Comments View Clickable
        lostcell.homeVC = self
        return lostcell


    case foundCollectionView:
        let foundcell: FoundCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "Foundcell", for: indexPath) as! FoundCollectionViewCell

        let post = newPostsFound[indexPath.row]
        foundcell.post = post

        //Make TextView Clickable
        foundcell.phoneFoundTextView.isEditable = false;
        foundcell.phoneFoundTextView.dataDetectorTypes = UIDataDetectorTypes.phoneNumber
        return foundcell

    case adoptionCollectionView:
        let adoptioncell: AdoptionCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "Adopotioncell", for: indexPath) as! AdoptionCollectionViewCell

        let post = postsadoption[indexPath.row]
        adoptioncell.post = post

        //Make TextView Clickable
        adoptioncell.phoneAdoptionTextView.isEditable = false;
        adoptioncell.phoneAdoptionTextView.dataDetectorTypes = UIDataDetectorTypes.phoneNumber
        return adoptioncell

    default:
        return UICollectionViewCell()
    }

    }

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {


    switch collectionView {

    case lostCollectionView:

        let vc = storyboard?.instantiateViewController(withIdentifier: "lostSelectedViewController") as? LostSelectedViewController
        self.navigationController?.pushViewController(vc!, animated: true)
        vc?.posts = posts[indexPath.row]
        break

    case foundCollectionView:
       let vc = storyboard?.instantiateViewController(withIdentifier: "foundSelectedViewController") as? FoundSelectedViewController
       self.navigationController?.pushViewController(vc!, animated: true)
        vc?.posts = newPostsFound[indexPath.row]
        break

    case adoptionCollectionView:
        let vc = storyboard?.instantiateViewController(withIdentifier: "adoptionSelectedViewController") as? AdoptionSelectedViewController
        self.navigationController?.pushViewController(vc!, animated: true)
        vc?.posts = postsadoption[indexPath.row]
        break

    default:
        break
    }

    func commentsViewPressed() {
        print("Hola")
        performSegue(withIdentifier: "commentSegue", sender: self)

    }
}

}

Answer 1

问题看起来像在此代码中

let postId = sender as! String
commentVC.postIdNew = postId

Sender指的是发起segue的对象，因此可能是按钮或TableViewCell（请参阅apples docs：https://developer.apple.com/documentation/uikit/uiviewcontroller/1621490-prepare）

您需要将sender as! String替换为您要设置的postId的值。我假设您可以从第一个视图控制器上的某处获得它。

Answer 2

实际上我的错误不在这里。我的错误是我的snapshot.key没有检索到childByAutoId，因此当我运行查询时，它给了我一个匹配的子项列表，并且由于没有单个结果，SDK会打印出您查询的位置/集合的键：posts

我要做的就是检索必须使用此行的childByAutoId：

 let key = childSnapshot.key as String

我在这个stackoverflow问题-> Firebase snapshot.key not returning actual key?

中找到了答案

如何将发布ID传递给评论VC-Swift

2 个答案: