ios - 只有最后 2 个值的索引超出范围？

Question

我目前的索引超出范围，但这仅在前 3 个项目成功显示后发生。我查看了代码，但我仍然不知道我哪里出错了。索引超出范围仅在尝试在单元格中加载文本时发生。

从 viewdidload 调用方法时的日志：

indexPath 描述：0 indexPath 描述：1 indexPath 描述：2

当我按下按钮加载其余图像时记录：

indexPath 描述：0 indexPath 描述：1 indexPath 描述：2 indexPath 描述：3

indexpath 超出范围的数据源方法：

    //MARK: - tableview datasource methods

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)

    if arrayOfImgObj.count > 0 {
        cell.imageView?.image = arrayOfImgObj[indexPath.row].imageTempt
        print("Description of indexPath: ",indexPath.row)
        cell.textLabel?.text = arrayOfUIDs[indexPath.row] // index out of range
    } else {
        print("\(arrayOfImgObj.count) not over 0 yet")
    }
    return cell
}

viewDidload 时调用的方法：

    //testing array
var arrayOfUIDs = User().users

func fetchAllUserFristImage() {
    Database.database().reference().child("Posts").observe(.childAdded, with: {(snapshot) in

        if (snapshot.value as? [String: AnyObject]) != nil {
            let user = User()

            user.id = snapshot.key

            //testing array
            self.arrayOfUIDs.append(snapshot.key)

            print("\(String(describing: user.id)) <-- SHUD BE THE USERUID")

            self.databaseRef = Database.database().reference()

            let usersPostRef2 = self.databaseRef.child("Posts").child(user.id!)

            usersPostRef2.observe(.value, with: {(postXSnapshots) in

                if let postDictionary2 = postXSnapshots.value as? NSDictionary {

                    for (p) in postDictionary2 {

                        let posts = p.value as! NSDictionary

                        //to get back to where i was delete the below for i
                        for (i) in posts {

                            let imageUrlString = i.value as! NSDictionary

                            guard let postUrl = imageUrlString.value(forKey: "image1") else {return}

                            //below is ting from below
                            if postUrl != nil {

                                self.feedArray.append(Post(fetchedImageURL: postUrl as! String))

                                let imageUrlString = "\(postUrl)"

                                let imageUrl = URL(string: imageUrlString)!
                                print("\(imageUrl) this shud be img url's of posts")

                                let imageDataL = try! Data(contentsOf: imageUrl)
                                self.imageObject.img2 = UIImage(data: imageDataL)
                                let image1ToDisplay: UIImage = self.imageObject.img2!
                                self.arrayOfImgObj.append(forTable(imageTempt: image1ToDisplay))

                            } else {print("this user had no posts, was nil")}
                        }
                    }
                }
            })
        }
        //below shud stay same
        DispatchQueue.main.async {
            self.tableView.reloadData()
        }
    })
}

编辑：

我已将代码更改为仅使用一个对象数组：

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)

    if arrayOfImgObj.count > 0 {
        cell.imageView?.image = arrayOfImgObj[indexPath.row].imageTempt
        print("Description of indexPath: ",indexPath.row)
        cell.textLabel?.text = arrayOfImgObj[indexPath.row].users[indexPath.row] // index out of range
    } else {
        print("\(arrayOfImgObj.count) not over 0 yet")
    }

    return cell
}

将函数中的一行更改为：

self.arrayOfImgObj.append(forTable(imageTempt: image1ToDisplay, users: snapshot.key))

提前致谢！

标签： iosarraysswiftfirebasefirebase-realtime-database

Answer 1

你的问题是你有两个数组：

• arrayOfUIDs每个用户都有一个条目
• arrayOfImgObj每个用户都有 0-n 个条目（因此，该数组中的对象数很可能大于arrayOfUIDs.

您的行数基于arrayOfImgObj，但随后使用行号来索引arrayOfUIDs，这会导致数组边界异常。

为每个用户 ID 设置表格视图部分可能会更优雅，但如果您想将所有行放在一个部分中，我建议您使用单个结构数组作为数据模型。

使用类似的东西：

struct UserImage {
    var userID: String
    var image: UIImage
}


var tableData = [UserImage]()

然后，当您获取每个图像时，创建一个新结构并将其放入您的数组中：

func fetchAllUserFristImage() {
    Database.database().reference().child("Posts").observe(.childAdded, with: {(snapshot) in

        if snapshot.value as? [String: AnyObject] != nil {
            let user = snapshot.key

            self.databaseRef = Database.database().reference()

            let usersPostRef2 = self.databaseRef.child("Posts").child(user)

            usersPostRef2.observe(.value, with: {(postXSnapshots) in

                if let postDictionary2 = postXSnapshots.value as? [String:AnyObject] {

                    for (p) in postDictionary2 {

                        if let posts = p.value as? [String:AnyObject] {

                            //to get back to where i was delete the below for i
                            for (i) in posts {

                                if let imageUrlString = i.value as? [String:AnyObject], let postUrl = imageUrlString.["image1"] as? String {

                                    self.feedArray.append(Post(fetchedImageURL: postUrl))
                                    if let imageUrl = URL(string: postUrl), let imageDataL = try? Data(contentsOf: imageUrl), let image = UIImage(data: imageDataL) {

                                        self.tableData.append(UserImage(userID: user, image: image))
                                    } else {print("this user had no posts, was nil")}
                                }
                            }
                        }
                    }
                }
            })
                //below shud stay same
                DispatchQueue.main.async {
                    self.tableView.reloadData()
            }
        }
    })

}

现在，您cellForRow可以：

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)

    cell.imageView?.image = tableData[indexPath.row].image
    cell.textLabel?.text = tableData[indexPath.row].userID

    return cell
}