为什么我的代码不工作？ - setObjectForKey：key不能为零

Question

处理将数据存储在Firebase上并将数据加载到我的TableView中的应用程序。必须从我找到的教程中稍微更改（旧）代码，以便我希望有人能够发现我犯的错误。用户可以添加一个事件：名称，日期，描述（所有字符串）和图像。这些数据被载入到三个“标签”和图像顶部。

import UIKit 
import Firebase 
import FirebaseDatabaseUI 

class EventViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate { 

    //outlets for text & image 
    @IBOutlet weak var photoImageView: UIImageView! 

    @IBOutlet weak var eventName: UITextField! 
    @IBOutlet weak var eventDate: UITextField! 
    @IBOutlet weak var eventDes: UITextView! 

    //Database connection 
    let rootref = FIRDatabase().reference() 
    var imagePicker: UIImagePickerController = UIImagePickerController() 



    override func viewDidLoad() { 
     super.viewDidLoad() 
    } 

    override func didReceiveMemoryWarning() { 
     super.didReceiveMemoryWarning() 
    } 

    @IBAction func submitEvent(sender: AnyObject) { 

     let name = eventName.text 
     let date = eventDate.text 
     let text = eventDes.text 
     var data: NSData = NSData() 

     if let image = photoImageView.image { 
      data = UIImageJPEGRepresentation(image,0.1)! 
     } 

     let base64String = data.base64EncodedStringWithOptions(NSDataBase64EncodingOptions.Encoding64CharacterLineLength) 

     let user: NSDictionary = ["name":name!, "date":date!, "text":text!, "photoBase64":base64String] 

     //Add firebase child node 
     let event = FIRDatabase().reference().child(name!) 

     // Write data to Firebase 
     event.setValue(user) 

     navigationController?.popViewControllerAnimated(true) 
    } 

    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) { 
     view.endEditing(true) 
     super.touchesBegan(touches, withEvent: event) 
    } 

    //UIImagePickerControllerDelegate methods 

    func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]) { 
     imagePicker.dismissViewControllerAnimated(true, completion: nil) 
     photoImageView.image = info[UIImagePickerControllerOriginalImage] as? UIImage 
    } 

    func imagePickerControllerDidCancel(picker: UIImagePickerController) { 
     dismissViewControllerAnimated(true, completion: nil) 
    } 

    @IBAction func addPicture(sender: AnyObject) { 
     if(UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.Camera)) { 
      imagePicker = UIImagePickerController() 
      imagePicker.delegate = self 
      imagePicker.sourceType = .Camera 

      presentViewController(imagePicker, animated: true, completion: nil) 
     } else { 
      imagePicker.allowsEditing = false 
      imagePicker.sourceType = .PhotoLibrary 
      imagePicker.delegate = self 
      presentViewController(imagePicker, animated: true, completion:nil) 
     } 
    } 
} 

我TABLEVIEWCONTROLLER

import UIKit 
import Firebase 

class EventTableViewController: UITableViewController { 

    @IBOutlet weak var eventImage: UIImageView! 
    @IBOutlet weak var eventName: UILabel! 
    @IBOutlet weak var eventDate: UILabel! 
    @IBOutlet weak var eventText: UITextView! 

    let rootref = FIRDatabase().reference() 
    var items = [NSDictionary]() 


    override func viewDidLoad() { 
     super.viewDidLoad() 
    } 

    override func viewDidAppear(animated: Bool) { 
     super.viewDidAppear(animated) 
     items = [NSDictionary]() 

     FIRDatabase.load() 
    } 

    override func didReceiveMemoryWarning() { 
     super.didReceiveMemoryWarning() 
    } 

    //TableView Data 
    override func numberOfSectionsInTableView(tableView: UITableView) -> Int { 
     return 1 
    } 

    override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int { 
     return items.count 
    } 

    override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell { 

     let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) 

     configureCell(cell, indexPath: indexPath) 

     return cell 
    } 

    override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) { 
     if editingStyle == .Delete { 

      let dict = items[indexPath.row] 
      let name = dict["name"] as! String 

      // delete data from firebase 

      let event = FIRDatabase().reference().child(name) 
      event.removeValue() 
     } 
    } 

    // MARK:- Configure Cell 

    func configureCell(cell: UITableViewCell, indexPath: NSIndexPath) { 
     let dict = items[indexPath.row] 

     eventName.text = dict["name"] as? String 
     eventDate.text = dict["name"] as? String 
     eventText.text = dict["name"] as? String 

     let base64String = dict["photoBase64"] as! String 
     populateImage(cell, imageString: base64String) 
    } 

    func populateImage(cell:UITableViewCell, imageString: String) { 

     let decodedData = NSData(base64EncodedString: imageString, options: NSDataBase64DecodingOptions.IgnoreUnknownCharacters) 

     let decodedImage = UIImage(data: decodedData!) 

     cell.imageView!.image = decodedImage 
    } 

    //load data from Firebase 
    func loadDataFromFirebase() { 

     UIApplication.sharedApplication().networkActivityIndicatorVisible = true 


      rootref.observeEventType(.Value, withBlock: { snapshot in 
       var tempItems = [NSDictionary]() 


      for item in snapshot.children { 
       let child = item as! FIRDataSnapshot 
       let dict = child.value as! NSDictionary 
       tempItems.append(dict) 
      } 

      self.items = tempItems 
      self.tableView.reloadData() 
      UIApplication.sharedApplication().networkActivityIndicatorVisible = false 

     }) 
    } 
} 

IMAGE让我的工作

My app so far

Answer 1

看这句话的想法：

let user: NSDictionary = ["name":name!, "date":date!, "text":text!, "photoBase64":base64String] 

你是在这里做了很多的强制解包。事实上，你在很多地方都做了很多的强制解包。当你这样做时，你会说：“我百分之百确定这里总是有价值的”。避免这几乎所有的成本。该行应该看起来像这样。

if let unwrappedName = name , unwrappedDate = date, unwrappedText = text{ 
    let user: NSDictionary = ["name":unwrappedName, "date":unwrappedDate, "text":unwrappedText, "photoBase64":base64String] 
} 

像这样展开选项会让您的应用程序崩溃。你应该在这里放置一个断点来看看什么值是零。每次你使用！你应该仔细考虑它。

Answer 2

我相信这个错误是你设置数据库连接的地方。

您有：let rootref = FIRDatabase().reference()

它应该是：let rootref = FIRDatabase().database().reference()

我得到了同样的错误，这个固定为我。