SWIFT: Difficultly displaying data in tableView - ios

Question

I am attempting to display data from Parse onto the following tableView controller. For some reason, the data is not displaying on the tableView (i.e. the rows are blank). I do not think that the data queried from Parse is being appended to the arrays. I am wondering what I'm doing wrong here.
Here's the current output:
I am using a custom prototype cell with identifier "CellTrack" class "TrackTableViewCell" and as shown below:
Here is my code in the TableViewController file:
import UIKit
import Parse
class MusicPlaylistTableViewController: UITableViewController {
var usernames = [String]()
var songs = [String]()
var dates = [String]()
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewWillAppear(animated: Bool) {
var query = PFQuery(className:"PlaylistData")
query.findObjectsInBackgroundWithBlock { (objects: [PFObject]?, error: NSError?) -> Void in
if error == nil {
if let objects = objects! as? [PFObject] {
self.usernames.removeAll()
self.songs.removeAll()
self.dates.removeAll()
for object in objects {
let username = object["username"] as? String
self.usernames.append(username!)
print("added username")
let track = object["song"] as? String
self.songs.append(track!)
let date = object["createdAt"] as? String
self.dates.append(date!)
self.tableView.reloadData()
}
}
} else {
print(error)
}
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
// MARK: - Table view data source
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 {
// #warning Incomplete implementation, return the number of rows
return usernames.count
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("CellTrack", forIndexPath: indexPath) as! TrackTableViewCell
cell.username.text = usernames[indexPath.row]
cell.songTitle.text = songs[indexPath.row]
cell.CreatedOn.text = dates[indexPath.row]
return cell
}
}
And here is my code in the "TrackTableViewCell.swift" class:
import UIKit
class TrackTableViewCell: UITableViewCell {
#IBOutlet weak var songTitle: UILabel!
#IBOutlet weak var username: UILabel!
#IBOutlet weak var CreatedOn: UILabel!
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
}
override func setSelected(selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
}

Answer 1

Execute your tableView.reloadData() in main thread.
dispatch_async(dispatch_get_main_queue(), {
self.tableViewCell.reloadData()
})

Answer 2

Try doing a guard let to see if those values are actually coming back as string or not. My guess would be that the value for created at never came back. Try it out and let me know.
guard let username = object["username"] as? String else {
print ("could not get username")
}
self.usernames.append(username)
print("added username")
guard let track = object["song"] as? String else {
print ("could not get song")
return
}
self.songs.append(track)
guard let date = object["createdAt"] as? String else {
print ("could not get createdAt")
return}
self.dates.append(date!)

Answer 3

func dequeueReusableCellWithIdentifier(_ identifier: String) -> UITableViewCell?
Return Value
A UITableViewCell object with the associated identifier or nil if no such object exists in the reusable-cell queue.
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var cell = tableView.dequeueReusableCellWithIdentifier("CellTrack", forIndexPath: indexPath) as! TrackTableViewCell
if cell == nil {
// create a new cell here
cell = TrackTableViewCell(...)
}
cell.username.text = usernames[indexPath.row]
cell.songTitle.text = songs[indexPath.row]
cell.CreatedOn.text = dates[indexPath.row]
return cell
}