从Firebase存储中检索图像以显示在tableView（Swift）上

Question

New Firebase的扩展问题检索数据并将其放在tableView（Swift）

通过将Firebase代码移动到viewDidLoad，Post的所有文本部分都可以显示出来。但是我仍然不能将图像放到tableView中。我已经检查了图像检索，并成功了，我想我从Firebase检索的图像不在发布数组中。

这是我的修复代码：

  import UIKit
  import Firebase
  import FirebaseStorage

class timelineTableViewController: UITableViewController {
var posts = [Post]()
var databaseRef: FIRDatabaseReference!
var storageRef: FIRStorageReference!

override func viewDidLoad() {
    super.viewDidLoad()
    databaseRef = FIRDatabase.database().reference()
    storageRef = FIRStorage.storage().reference()
    let userPostRef = self.databaseRef.child("posts")
    userPostRef.queryOrderedByChild("time").observeEventType(.ChildAdded, withBlock: {(snapshot) in
        if let postAdd  = snapshot.value as? NSDictionary{

            let url = snapshot.value?["postPhoto"] as! String
            let userPhotoUrl = snapshot.value?["userPhoto"] as! String
            let myPost = Post(data: postAdd)

            FIRStorage.storage().referenceForURL(url).dataWithMaxSize(10 * 1024 * 1024, completion: { (data, error) in
                let postPhoto = UIImage(data: data!)

                                    })
            FIRStorage.storage().referenceForURL(userPhotoUrl).dataWithMaxSize(10 * 1024 * 1024, completion: { (data, error) in
                let userPhoto = UIImage(data: data!)
                                })

            self.posts.insert(myPost, atIndex: 0)
            self.tableView.reloadData()

        }




})

}
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    // #warning Incomplete implementation, return the number of sections
    return 1
}

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


}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cellIdentifier = "postCell"
    let cell = tableView.dequeueReusableCellWithIdentifier(cellIdentifier, forIndexPath: indexPath)as! timelineTableViewCell
    //Dispatch the main thread here
    dispatch_async(dispatch_get_main_queue()) {
        cell.usernameLabel.text = self.posts[indexPath.row].username
        cell.postText.text = self.posts[indexPath.row].postText
        cell.timeLabel.text = self.posts[indexPath.row].time
        cell.postPhoto.image = self.posts[indexPath.row].postPhoto
        cell.userPhoto.image = self.posts[indexPath.row].userPhoto


    }
    return cell
   }
   }

我的Post结构希望对您有所帮助！

struct  Post {
var username: String?
var postText: String?
var time: String?
var userPhoto: UIImage?
var postPhoto: UIImage?
var url: String?
var userPhotoUrl:String?
init(data: NSDictionary) {
   username = data["username"] as? String
   postText = data["postText"] as? String
    time = data["time"]as? String
    userPhoto = data["userPhoto"] as? UIImage
    postPhoto = data["postPhoto"] as? UIImage
    url = data["postPhoto"] as? String
    userPhotoUrl = data["userPhoto"] as? String
}

}

希望能得到一些建议！

Answer 1

只需更改以下方法

func downloadPost(){
    let userPostRef = self.databaseRef.child("posts")

    userPostRef.queryOrderedByChild("time").observeEventType(.ChildAdded, withBlock: {(snapshot) in
        if let postAdd  = snapshot.value as? NSDictionary {
            print("\(snapshot.value)")
            let url = snapshot.value?["postPhoto"] as! String
            let userPhotoUrl = snapshot.value?["userPhoto"] as! String

            var myPost = Post(data: postAdd) //variable change to "var" because going to modify

            let url2 = NSURL(string: url)  //postPhoto URL
            let data = NSData(contentsOfURL: url2!) // this URL convert into Data
            if data != nil {  //Some time Data value will be nil so we need to validate such things 
             myPost.postPhoto = UIImage(data: data!)
            }


            let url3 = NSURL(string: userPhotoUrl)  //userPhoto URL
            let data2 = NSData(contentsOfURL: url3!)  //Convert into data
            if data2 != nil  {  //check the data
            myPost.userPhoto = UIImage(data: data2!)  //store in image
            }




            self.posts.insert(myPost, atIndex: 0)  // then add the "myPost"  Variable
            print(self.posts.count)
        }
        self.tableView.reloadData()  // finally going to load the collection of data in tableview
    })


}

它需要大量的加载时间。因为转换图像并将其存储在主队列中。

另一种方法是存储URL并在表视图显示中访问URL。可以在imageview中应用异步加载。