ios - viewDidLoad 中的变量未填充自定义表格单元格

Question

我需要采用 viewDidLoad 方法中填充的变量来显示在连接到自定义单元格的标签上。我想做的是:

1. 查找数据库中存储的用户盒子中的 SKU
2. 使用SKU查找数据库中存储的产品详细信息
3. 将产品详细信息存储在适当的变量中
4. 获取所述变量并在自定义表格单元格中填充标签

问题是我可以将变量存储在 viewDidLoad 方法中，但是当我尝试调用该变量来填充自定义表格单元格时，该变量为空。

我正在使用 Firebase 来存储数据。 Fire Base节点设置如下，节点1:产品/Sku/商品详细信息节点2:Box/UID/Skus

"products" : {
    "0123456" : {
      "brand" : "Nike",
      "item_name" : "basketball"
    }
  },
  "box" : {
    "jEI5O8*****UID" : {
      "sku" : "0123456"

我一直在堆栈溢出、YouTube、谷歌等搜索，但我似乎找不到解决方案...如果你能帮助我指出正确的方向，我将不胜感激!仅供引用，我是 swift/firebase 的新手。

import UIKit
import FirebaseAuth
import FirebaseDatabase

class drawerFaceExampleViewController: UIViewController, UITableViewDelegate,UITableViewDataSource {

    var databaseRef = FIRDatabase.database().reference()
    var loggedInUser = AnyObject?()
    var loggedInUserData = AnyObject?()
    var itemDrawer = AnyObject?()
    var dataDict = AnyObject?()

    @IBOutlet weak var homeTableView: UITableView!

    var item_name = String()
    var brand_name = String()




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


        self.loggedInUser = FIRAuth.auth()?.currentUser


        //get the logged in users details
        self.databaseRef.child("user_profiles").child(self.loggedInUser!.uid).observeSingleEventOfType(.Value) { (snapshot:FIRDataSnapshot) in

            //store the logged in users details into the variable

            self.loggedInUserData = snapshot

            //get all the item sku's that are in the user's box

            self.databaseRef.child("box/\(self.loggedInUser!.uid)").observeEventType(.ChildAdded, withBlock: { (snapshot:FIRDataSnapshot) in


                let sku = snapshot.value! as! String

//access the 'products' node to extract all the item details
                self.databaseRef.child("products").child(sku).observeSingleEventOfType(.Value, withBlock: { (snapshot:FIRDataSnapshot) in

                    if let itemvariable = snapshot.value!["item"] as? String {
                        self.item_name = item variable

                        //testing to see if item name is stored, works!
                        print("testing=", self.item_name)
                    }
                    if let brandvariable = snapshot.value!["brand"] as? String{
                        self.brand_name = brand variable

                        //testing to see if brand name is stored, works!
                        print("testingBrand =", self.brand_name)
                    }

                })


                 self.homeTableView.insertRowsAtIndexPaths([NSIndexPath(forRow:0,inSection:0)], withRowAnimation: UITableViewRowAnimation.Automatic)

            }){(error) in

                print(error.localizedDescription)
            }

        }

    }

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


    func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return 1
    }

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

    }

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

        let cell: drawerFaceExampleTableViewCell = tableView.dequeueReusableCellWithIdentifier("drawerFaceExampleCell", forIndexPath: indexPath) as! drawerFaceExampleTableViewCell

        //checking to see the item & brand name has been extracted...but blank :( 

        print("item_name=",self.item_name)
        print("item_name=",self.item_name)

       //this is where item & brand name extracted from viewDidLoad to display in the cell.
        cell.configure(nil, brandName: brand_name, itemName: item_name)


        return cell
    }

}

Answer 1

听起来当您去读取变量时您的数据尚未完成加载。下载完成后，您需要在完成处理程序中更新 UI:

if let itemvariable = snapshot.value!["item"] as? String {
    self.item_name = item variable

    //testing to see if item name is stored, works!
    print("testing=", self.item_name)
}

if let brandvariable = snapshot.value!["brand"] as? String{
    self.brand_name = brand variable

    //testing to see if brand name is stored, works!
    print("testingBrand =", self.brand_name)
}

// Update UI here.