使用 Firebase Firestore 更新 TableViewCell 中的按钮 UI

Question

我的应用中的“关注”按钮和“喜欢”按钮都存在同样的问题。

我在 Firebase Firestore 文档中看到了如何在按下时添加数据以及如何删除记录，但是，我在更新视图加载时要选择或不选择的按钮的初始状态时遇到了问题。

这会在 awakeWithNib 中完成吗？你会添加一个快照监听器吗？

FollowerCell.swift

class FollowerCell: UITableViewCell {

// MARK: - Outlets
@IBOutlet weak var friendImageView: UIImageView!
@IBOutlet weak var nameLabel: UILabel!
@IBOutlet weak var followButton: SpringButton!

// MARK: - Variables
var userId:String!
var db:Firestore!

override func awakeFromNib() {
    super.awakeFromNib()
    // Initialization code
    friendImageView.layer.masksToBounds = true

    db = Firestore.firestore()

    self.setFollowingButton()
}

// MARK: - Functions
func setFollowingButton() {
    if let currentUser = Auth.auth().currentUser {
        let followerDB = db.collection("users").document(currentUser.uid).collection("followers").whereField("follower", isEqualTo: true)
        followerDB.getDocuments { (querySnapshot, error) in
            if let error = error {
                print("Error getting documents: \(error)")
            } else {
                DispatchQueue.main.asyncAfter(deadline: .now() + 1, execute: {
                    self.followButton.isSelected = true
                })
            }
        }
    }
}

@IBAction func followButtonPressed(_ sender: UIButton) {
    if followButton.isSelected == true {
        followButton.isSelected = false
        // add follower
        if let user = Auth.auth().currentUser {
            Firestore.firestore().collection("users").document(user.uid).collection("following").document("\(userId!)").setData([
                "name":self.nameLabel.text ?? "",
                "following":true
            ])  { err in
                if let err = err {
                    print("Error writing document: \(err)")
                } else {
                    print("\(self.userId!) added to followers")
                }
            }
        }
    } else {
        followButton.isSelected = true
        // delete following
        if let user = Auth.auth().currentUser {
            Firestore.firestore().collection("users").document(user.uid).collection("following").document("\(userId!)").delete() { err in
                if let err = err {
                    print("Error removing document: \(err)")
                } else {
                    print("\(self.userId!) successfully removed!")
                }
            }
        }
    }

}

Answer 1

class FollowersTableViewController: UITableViewController {

// MARK: - Variables
var db:Firestore!
let storage = Storage.storage().reference()
var followerArray = [User]()
var followingArray = [String]()

// MARK: - ViewDidLoad
override func viewDidLoad() {
    super.viewDidLoad()

    db = Firestore.firestore()

    SVProgressHUD.show()
    getFollowers()
    getFollowing()

    self.tableView.reloadData()

}

// MARK: - Table view data source

override func numberOfSections(in tableView: UITableView) -> Int {
    return 1
}

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

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "followerCell", for: indexPath) as! FollowerCell

    // Configure the cell...
    let user = followerArray[indexPath.row]

    cell.nameLabel.text = user.name
    cell.userId = user.documentId
    // Set follow button state
    if followingArray.contains(cell.userId) {
        cell.followButton.isSelected = false
    } else {
        cell.followButton.isSelected = true
    }

    let userImageRef = storage.child("\(user.documentId)"+"/profile_pic.jpg")
    // Download in memory with a maximum allowed size of 1MB (1 * 1024 * 1024 bytes)
    userImageRef.getData(maxSize: 1 * 1024 * 1024) { (data, error) in
        if let error = error {
            // Uh-oh, an error occurred! Display Default image
            print("Error - unable to download image: \(error)")
            cell.friendImageView.image = UIImage(named: "userProfileGray")
        } else {
            // Data for "locationImages/(locationId).jpg" is returned
            cell.friendImageView.image = UIImage(data: data!)
        }
        SVProgressHUD.dismiss()
    }

    return cell
}

override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    return 71
}

// MARK: - Functions
func getFollowers() {
    if let user = Auth.auth().currentUser {
        let followingDB = db.collection("users").document("\(user.uid)").collection("followers").whereField("follower", isEqualTo: true)
        followingDB.getDocuments { (querySnapshot, error) in
            if let error = error {
                print("Error getting documents: \(error)")
            } else {
                for document in (querySnapshot?.documents)! {
                    self.followerArray.append(User(name: document["name"] as! String, documentId: document.documentID))
                }
                DispatchQueue.main.async {
                    self.tableView.reloadData()
                }
            }
        }
    }
}

func getFollowing() {
    if let currentUser = Auth.auth().currentUser {
        let followingDB = db.collection("users").document(currentUser.uid).collection("following").whereField("following", isEqualTo: true)
        followingDB.getDocuments { (querySnapshot, error) in
            if let error = error {
                print("Error getting documents: \(error)")
            } else {
                for document in (querySnapshot?.documents)! {
                    self.followingArray.append(document.documentID)
                }
                DispatchQueue.main.async {
                    self.tableView.reloadData()
                }
            }
        }
    }
}

}