表格视图未使用Firebase更新

Question

I am trying to get a table view to update from my Firebase database. My data is structured like this (for reporting automobiles):

1. Reports:
   • Randomly generated report ID number:
   • • make: "make of car"
   • • model: "make of model"

I don't think that I am calling the data correctly. I do not know how to select for the random report ID. But there may be something else that I am missing. I am trying to get only the make and model of the vehicle to display in the text of the cell

var reportList:[String] = []

var ref: DatabaseReference!

var handle: DatabaseHandle?


@IBOutlet weak var reportsTableView: UITableView!

@IBAction func backButtonPressed(_ sender: UIBarButtonItem) {
    self.performSegue(withIdentifier: "reportsToHome", sender: self)
}

public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return reportList.count

}


public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell{
    let cell = UITableViewCell(style: .default, reuseIdentifier: "cell")

    cell.textLabel?.text = reportList[indexPath.row]

    return cell
}


override func viewDidLoad() {
    super.viewDidLoad()

    ref = Database.database().reference()

    handle = ref.child("Reports").observe(.childAdded, with: { (snapshot) in
        if (snapshot.value as? String) != nil
        {
            let make = String(describing: self.ref.child("Reports").child("make"))
            let model = String(describing: self.ref.child("Reports").child("model"))
            self.reportList.append(make + model)

            self.reportsTableView.reloadData()
        }
    }

    // Do any additional setup after loading the view.
)}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

Answer 1

I'm not able to test this, but I have feeling that you were trying to cast the snapshot as a string. Instead, you should cast it as a Dictionary so you can easily retrieve the data by key.

Try this code. It sets the snapshot as a dictionary, and from there you are able to retrieve the make and model:

override func viewDidLoad() {
super.viewDidLoad()

ref = Database.database().reference()

handle = ref.child("Reports").observe(.childAdded, with: { (snapshot) in
   if let reports = snapshot.value as? NSDictionary {
        var make = reports?["make"] as? String
        var model = reports?["model"] as? String

        self.reportList.append(make + model)
        self.reportsTableView.reloadData()
    }
}
)}

Going further, you can create a Report class:

class Report: NSObject {
    var make: String?
    var model: String?
}

You can then set the make and model from the snapshot to create a new Report object.

var make = reports?["make"] as? String
var model = reports?["model"] as? String
let newReport = Report()
newReport.setValuesForKeys(reports)

I hope this works, if not I'll look again.