所以我有一个tableview控制器，它有标题和单元格，应该存在于这些标题下。我已经完成了正确创建标题的工作。我目前已经为单元格准备了数据源，该数据源从用户当前参加的currentEvents列表中获取其内容。问题不在于数据的拉动似乎是完成块。需要很长时间才能返回到currentEvents数组永远不会被追加到它应该的时候。即使在进入新部分后应重置事件，它也会将事件附加到原始数组上。我尝试了很多东西，并在许多地方移动代码，但似乎没有任何效果
所有这一切的关键功能是
self.fetchEventsFromServer（）
特别是发生EventService.show的部分
import UIKit
import Firebase
class FriendsEventsView: UITableViewController{
var cellID = "cellID"
var friends = [Friend]()
var attendingEvents = [Event]()
//label that will be displayed if there are no events
var currentUserName: String?
var currentUserPic: String?
var currentEventKey: String?
override func viewDidLoad() {
super.viewDidLoad()
self.title = "Friends Events"
view.backgroundColor = .white
// Auto resizing the height of the cell
tableView.estimatedRowHeight = 44.0
tableView.rowHeight = UITableViewAutomaticDimension
self.navigationItem.rightBarButtonItem = UIBarButtonItem(image: #imageLiteral(resourceName: "close_black").withRenderingMode(.alwaysOriginal), style: .done, target: self, action: #selector(self.goBack))
tableView.register(EventDetailsCell.self, forCellReuseIdentifier: cellID)
self.tableView.tableFooterView = UIView(frame: CGRect.zero)
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
DispatchQueue.global(qos: .background).async {
print("This is run on the background queue")
self.fetchEventsFromServer { (error) in
if error != nil {
print(error)
return
} else {
DispatchQueue.main.async {
self.tableView.reloadData()
print("This is run on the main queue, after the previous code in outer block")
}
}
}
}
}
@objc func goBack(){
dismiss(animated: true)
}
override func numberOfSections(in tableView: UITableView) -> Int {
// print(friends.count)
return friends.count
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// print(friends[section].events.count)
return friends[section].collapsed ? 0 : friends[section].events.count
}
func tableView(_ tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
return UITableViewAutomaticDimension
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellID) as! EventDetailsCell? ?? EventDetailsCell(style: .default, reuseIdentifier: cellID)
// print(indexPath.row)
cell.details = friends[indexPath.section].events[indexPath.row]
return cell
}
override func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let header = tableView.dequeueReusableHeaderFooterView(withIdentifier: "header") as? CollapsibleTableViewHeader ?? CollapsibleTableViewHeader(reuseIdentifier: "header")
// print(section)
header.arrowLabel.text = ">"
header.setCollapsed(friends[section].collapsed)
print(friends[section].collapsed)
header.section = section
// header.delegate = self
header.friendDetails = friends[section]
return header
}
override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return 50
}
func fetchEventsFromServer(_ completion: @escaping (_ error: Error?) -> Void ){
//will grab the uid of the current user
guard let myUserId = Auth.auth().currentUser?.uid else {
return
}
let ref = Database.database().reference()
//checking database for users that the current user is following
ref.child("following").child(myUserId).observeSingleEvent(of: .value, with: { (followingSnapshot) in
//handling potentail nil or error cases
guard let following = followingSnapshot.children.allObjects as? [DataSnapshot]
else {return}
//validating if proper data was pulled
let group = DispatchGroup()
for followingId in following {
group.enter()
print(followingId.key)
ref.child("users").child(followingId.key).observeSingleEvent(of: .value, with: { (userInfoSnapShot) in
guard let followingUserInfo = userInfoSnapShot.children.allObjects as? [DataSnapshot] else {
return
}
//validating if proper data was pulled for each follower
for currentUserInfo in followingUserInfo {
//will add this back when I want to event implementation
if currentUserInfo.key == "Attending" {
guard let eventKeys = currentUserInfo.children.allObjects as? [DataSnapshot] else{return}
for event in eventKeys {
print(event.key)
EventService.show(forEventKey: event.key, completion: { (event) in
guard let currentEvent = event else{
return
}
self.attendingEvents.append(currentEvent)
print(self.attendingEvents.count)
})
}
}
if currentUserInfo.key == "profilePic"{
self.currentUserPic = currentUserInfo.value as! String
//print(self.currentUserPic)
}
if currentUserInfo.key == "username"{
self.currentUserName = currentUserInfo.value as! String
//print(self.currentUserName)
var friend = Friend(friendName: self.currentUserName!, events: self.attendingEvents, imageUrl: self.currentUserPic!)
print(friend.events.count)
self.friends.append(friend)
//print(self.friends.count)
}
}
group.leave()
let result = group.wait(timeout: .now() + 0.01)
completion(nil)
}, withCancel: { (err) in
completion(err)
print("Couldn't grab info for the current list of users: \(err)")
})
}
completion(nil)
}) { (err) in
completion(err)
print("Couldn't grab people that you are currently following: \(err)")
}
}
}
如果有人看到某些东西，请不要犹豫，不要犹豫 如何更改我的调度组实施以实现此目标
EventService功能
struct EventService {
static func show(forEventKey eventKey: String, completion: @escaping (Event?) -> Void) {
// print(eventKey)
let ref = Database.database().reference().child("events").child(eventKey)
// print(eventKey)
//pull everything
ref.observeSingleEvent(of: .value, andPreviousSiblingKeyWith: { (snapshot,eventKey) in
// print(snapshot.value ?? "")
guard let event = Event(snapshot: snapshot) else {
return completion(nil)
}
completion(event)
})
}
}