firebase正在从数据库中检索已删除的数据 [英] firebase is retrieving deleted data from database

问题描述

我使用的是Firebase实时数据库，对于我的应用程序的某些部分，它工作正常。我正在阅读YouTube上的一个教程，该教程向用户填充collectionView。它使用NSDictionary来获取照片URL和用户名，并把它们放在所有用户的集合视图中。我直接在Firebase控制台中删除了一些用户，现在只有一个用户。由于某种原因，它仍然拉我删除的用户。这是collectionView文件。

  import UIKit 
 import FirebaseDatabase 
 $ b $ private let reuseIdentifier =UserSearchCell
 
 class UsersCollectionViewController：UICollectionViewController {
 
 var userDict = NSDictionary？（）
 var userNamesArray = [String]（）
 var userImagesArray = [String]（）
 
重写func viewDidLoad（）{
 super.viewDidLoad（）
 DataService.ds.REF_USERS.observeEventType（.Value，withBlock：{
（snapshot）in 
 self.usersDict = snapshot.value as？NSDictionary 
 for（userId，details）in self.usersDict！{
 let img = details.objectForKey（profileThumbUrl）as！String 
让name = detail.objectForKey（username）as！String 
 self.userImagesArray.append（img）
 self.userNamesArray.append（name）
 self.collectionView？.reloadData（） 
} 
}）
 
 self.collectionView！.registerClass（UICollectionVie wCell.self，forCellWithReuseIdentifier：reuseIdentifier）
} 
 
覆盖func numberOfSectionsInCollectionView（collectionView：UICollectionView） - > Int {
 return 1 
} 
 
覆盖func collectionView（collectionView：UICollectionView，numberOfItemsInSection section：Int） - > Int {
 return self.userImagesArray.count 
} 
 
覆盖func collectionView（collectionView：UICollectionView，cellForItemAtIndexPath indexPath：NSIndexPath） - > UICollectionViewCell {
 let cell = collectionView.dequeueReusableCellWithReuseIdentifier（reuseIdentifier，forIndexPath：indexPath）as！ UserSearchCell 
 
 let imageUrl = NSURL（string：userImagesArray [indexPath.row]）
 let imageData = NSData（contentsOfURL：imageUrl！）
 cell.userImage.image = UIImage（data ：imageData！）
 cell.userName.text = userNamesArray [indexPath.row] 
 
 return cell 
} 
  

}

不应该总是与数据库同步吗？这些被删除的用户来自哪里？此外，我没有包含单元格代码，因为它只是声明的imageView和Label操作。我之前遇到过这个问题，但是我的记忆不好，我不记得为什么这样做，或者如果我解决了它。

解决方案

好吧，我想出了我自己的问题的答案。显然模拟器有一个firebase的问题，似乎形成某种缓存的firebase数据。我试着在我测试的手机上运行它，它没有这个缓存，一切正常。此外，我试着在模拟器上的另一个设备上运行，它也在那里工作得很好。所以我想留下来，因为我认为很多人可能会遇到与Firebase有关的问题，因为它的核心功能与IOS模拟器不兼容。

I'm using firebase realtime database and it's working fine for some parts of my app. I was going through a tutorial on youtube which populates a collectionView with users. It uses NSDictionary to get the photo URL and username and puts them in the collection view for all users. I deleted some of the users directly in the firebase console, and now have only one user. For some reason it's still pulling the users that I deleted. This is the collectionView file.

import UIKit
import FirebaseDatabase

private let reuseIdentifier = "UserSearchCell"

class UsersCollectionViewController: UICollectionViewController {

var usersDict = NSDictionary?()
var userNamesArray = [String]()
var userImagesArray = [String]()

override func viewDidLoad() {
    super.viewDidLoad()
    DataService.ds.REF_USERS.observeEventType(.Value, withBlock :{
        (snapshot) in
        self.usersDict = snapshot.value as? NSDictionary
        for(userId,details) in self.usersDict!{
            let img = details.objectForKey("profileThumbUrl") as! String
            let name = details.objectForKey("username") as! String
            self.userImagesArray.append(img)
            self.userNamesArray.append(name)
            self.collectionView?.reloadData()
        }
    })

    self.collectionView!.registerClass(UICollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)
}

override func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
    return 1
}

override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return self.userImagesArray.count
}

override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! UserSearchCell

    let imageUrl = NSURL(string:userImagesArray[indexPath.row])
    let imageData = NSData(contentsOfURL: imageUrl!)
    cell.userImage.image = UIImage(data:imageData!)
    cell.userName.text = userNamesArray[indexPath.row]

    return cell
}

}

Shouldn't this always sync with the database? Where are these deleted users coming from? Also I didn't include the cell code because all it is is the imageView and Label actions being declared. I ran into this problem before but my memory is bad and I don't remember why it was doing it or if I ever solved it.

解决方案

Okay I figured out the answer to my own question. Apparently the simulator has a problem with firebase and seems to form some sort of cache of firebase data. I tried running it on a phone I had been testing on and it didn't have this cache and everything worked fine. Also I tried running on a different device IN the simulator and it worked fine there too. So I want to leave this up because I think a lot of people may have trouble with Firebase since it's core feature doesn't work well with the IOS simulator.

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