Question

我正在尝试制作一个简单的iOS应用程序（最新版本的Xcode，Swift 3）。它所要做的就是从Firebase数据库下载某种对象，并生成包含所有信息的动态列表。我确保应用程序可以正确下载所有信息，当然也可以，但是当生成de TableView的时间到来时，它会发生灾难性的失败。这是代码：

var ref: DatabaseReference!
var refHandle:UInt!
var productList = [Product]()
@IBOutlet weak var myTable: UITableView!


let cellId = "Product"

override func viewDidLoad() {
    super.viewDidLoad()
    ref = Database.database().reference()
    myTable.delegate = self
    myTable.dataSource = self

    fetchProducts()

}

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

func tableView(tableView: UITableView,
               cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath as IndexPath) as! ProductTableViewCell

    cell.nameLabel.text = productList[indexPath.row].name
    cell.priceLabel.text = "" + (productList[indexPath.row].price?.description)!

    let imageDict:NSDictionary = productList[indexPath.row].imageName!
    let imageDownloaded = downloadImageProductFromFirebase(append: imageDict["hash"] as! String)
    cell.picture.image = imageDownloaded

    return cell
}

func fetchProducts(){

    self.productList.removeAll()
    refHandle = ref.child("products").observe(.childAdded, with: {(snapshot) in
        print(snapshot)

        var i = 0

        for element in snapshot.children
        {
            i = i + 1

              let item:DataSnapshot = element as! DataSnapshot
              let key = item.key
              let productsRef = self.ref!.child("products").child(key)
            productsRef.observe(.value, with: { snapshot in

                let productItem = (snapshot ).value as? [String : AnyObject]
                let product = Product(name: productItem?["name"] as! String, image: productItem?["image"] as! NSDictionary, price: productItem?["price"] as! Float)
                self.productList.append(product)
                self.tableView.reloadData()

            })
        }
    })
}


func downloadImageProductFromFirebase(append:String) -> UIImage{
    let storage = Storage.storage()
    var image = UIImage ()
    var reference: StorageReference!
    //all I did here was remove self before storage
    reference = storage.reference(forURL: "gs://fridgeapp-3e2c6.appspot.com/productImages/" + append)
    reference.downloadURL { (url, error) in

        if(error != nil){
        let data = NSData(contentsOf: url!)
        image = UIImage(data: data! as Data)!
        }
        else {
            image = #imageLiteral(resourceName: "ic_store")
        }
    }
    return image
}

此外，我拍了一张显示错误的图片（它在控制台上没有说明，只是这个）：Image of the error

毋庸置疑，我对Swift编程完全陌生，而且我在互联网上搜索，什么都没有......任何善良的灵魂都可以帮助我？在此先感谢!!

我甚至不知道这是什么样的错误

0 个答案: