ios - 通过数组 Firebase 实现 TableView 图像异步

Question

如何迭代我的数组

generalRoomDataArr

在涉及 UI 图像时更改发布到 TableView 的值。现在我上传了一张照片 URL 图像，但我想在更新 firebase URL 时更改数组中的图像。我能做什么我应该怎么做。

func initializeArray() {

        let ref = FIRDatabase.database().reference()
        //let userID = FIRAuth.auth()?.currentUser?.uid

        ref.child("general_room").queryOrderedByKey().observe(.childAdded, with: {snapshot in

            let snapDict = snapshot.value as? NSDictionary
            let message = snapDict?["Message"] as? String ?? ""
            let username = snapDict?["user_name"] as? String ?? ""
            let userIDString = snapDict?["uid"] as? String ?? ""
            let firebaseUserPhotoURL = snapDict?["photo_url"] as? String ?? ""

            //Time String from Firbase Database
            let timeString = snapDict?["time_stamp"] as? String ?? "2017-03-06 00:20:51"

            //timeAgoSinceDate - Format and call function to recieve time of post
            let dateFormatter = DateFormatter()
            dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
            let timeStampDate = dateFormatter.date(from: timeString)
            let timeStamp = timeAgoSinceDate(date: timeStampDate!, numericDates: false)


            //Assign array values
            self.generalRoomDataArr.insert(postStruct(username: username, message: message, photoURL: firebaseUserPhotoURL, timeStamp: timeStamp, cellUserId: userIDString), at: 0)
            self.tableView.reloadData()


        })

}//END FUNCTION

按钮/表格 View

//Message Send button is pressed data uploaded to firebase
    @IBAction func sendButtonPressed(_ sender: UIButton) {


        //If a character exists will be uploaded to firebase
        if ((messageTextField.text?.characters.count)! > 0) {

        let message : String = self.messageTextField.text!


        UploadGeneralChatRoom(message: message) //upload to general_room


        self.messageTextField.text = nil
        messageTextField.resignFirstResponder()//Quit keyboard

        self.tableView.reloadData() //Reload tableView
        //UploadUserData() //Update Rank in database

        }

    }


func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCell(withIdentifier: "cell")


        //initialize UI Profile Image
        let imageView = cell?.viewWithTag(3) as! UIImageView

        //Make Porfile Image Cirlce
        imageView.layer.cornerRadius = imageView.frame.size.width/2
        imageView.clipsToBounds = true


        //Loading and change of Usesrs profile image on chat cell
        let userProfileChatImage = generalRoomDataArr[indexPath.row].photoURL

        //Load profile image(on cell) with URL & Alamofire Library
        let downloadURL = NSURL(string: userProfileChatImage!)
        imageView.af_setImage(withURL: downloadURL as! URL)



        // your cell coding
        return cell!
    }

Firebase

func UploadGeneralChatRoom(message : String) {

    //Firebase Initialization
    var ref: FIRDatabaseReference!
    //var storage: FIRStorageReference!
    let userID = FIRAuth.auth()?.currentUser?.uid
    ref = FIRDatabase.database().reference()
    //storage = FIRStorage.storage().reference()


    //Get Data from database resend to database
    if let userId = userID {
    ref.child("Users").child(userID!).observeSingleEvent(of: .value, with: {(snapshot) in

        let snapDict = snapshot.value as? NSDictionary
        let username = snapDict?["Username"] as? String ?? ""
        let firebaseUserPhotoURL = snapDict?["photo_url"] as? String ?? ""
        let userRank = snapDict?["user_rank"] as? String ?? ""

        let now = Date()
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
        let nowString = dateFormatter.string(from: now)


        //Update general_room information about user
        ref.child("general_room").childByAutoId().setValue(["user_name": username, "uid": userId, "Message" : message, "time_stamp" : nowString, "photo_url" : firebaseUserPhotoURL])


        //Update User Rank - transforming String to Int back to String for firebase
        if var userRankInt = Int(userRank) {
            userRankInt += 1 //Increment User Rank every post
            let userRankString = String(userRankInt) //Convert Int back to String
            //Update User Rank of the current user everytime they post
            ref.child("Users").child(userID!).updateChildValues(["user_rank": userRankString])

        }



    })

}

Answer 1

您可以向 UploadGeneralChatRoom 方法添加回调。例如:

func UploadGeneralChatRoom(message : String, success: (()->())?)

然后在收到快照时调用成功回调；

ref.child("Users").child(userID!).observeSingleEvent(of: .value, with: {(snapshot) in
    success?()
    let snapDict = snapshot.value as? NSDictionary
    let username = snapDict?["Username"] as? String ?? ""
    let firebaseUserPhotoURL = snapDict?["photo_url"] as? String ?? ""
    let userRank = snapDict?["user_rank"] as? String ?? ""

    let now = Date()
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
    let nowString = dateFormatter.string(from: now)


    //Update general_room information about user
    ref.child("general_room").childByAutoId().setValue(["user_name": username, "uid": userId, "Message" : message, "time_stamp" : nowString, "photo_url" : firebaseUserPhotoURL])


    //Update User Rank - transforming String to Int back to String for firebase
    if var userRankInt = Int(userRank) {
        userRankInt += 1 //Increment User Rank every post
        let userRankString = String(userRankInt) //Convert Int back to String
        //Update User Rank of the current user everytime they post
        ref.child("Users").child(userID!).updateChildValues(["user_rank": userRankString])

    }



})

此成功回调返回void，您可以根据需要传递您的url。但在这种情况下，您只需要知道它是否更新即可。