自定义UITableViewCells未出现在UI TableView上

Question

I am developing an app, and I have a TableView within my ViewController that I want to display custom UITableViewCells. Here is my view controller class as it pertains to the table view:

import UIKit
import MapKit
import CoreLocation
import Firebase
import FirebaseAuth
import FirebaseDatabase


class FirstViewController: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate, UITableViewDelegate, UITableViewDataSource {

@IBOutlet weak var taskTable: UITableView!
var tasks = [Task]()
var locationCurrent: CLLocation?
private var _ref = FIRDatabase.database().reference()


var ref: FIRDatabaseReference {
    return _ref
}


@IBOutlet weak var welcomeLabel: UILabel!


var _user = FIRAuth.auth()?.currentUser

let cellIdentifier = "TaskTableViewCell"

@IBOutlet weak var homeMap: MKMapView!
let locationManager = CLLocationManager()

override func viewDidLoad() {
    super.viewDidLoad()
    self.locationManager.delegate = self
    self.homeMap.delegate = self
    self.locationManager.desiredAccuracy = kCLLocationAccuracyBest
    self.locationManager.requestWhenInUseAuthorization()
    self.locationManager.startUpdatingLocation()
    getMapAnnotations()
    self.taskTable.registerClass(UITableViewCell.self, forCellReuseIdentifier: "cell")
    loadTasks()
    taskTable.delegate = self
    taskTable.dataSource = self

    var refHandle = self.ref.child("user_profile").observeEventType(FIRDataEventType.Value, withBlock: { (snapshot) in
        let usersDict = snapshot.value as? NSDictionary
        let userDetails = usersDict?.objectForKey((self._user?.uid)!)

        if (userDetails?.objectForKey("name") != nil) {
        self.welcomeLabel.text = "Welcome, \(userDetails?.objectForKey("name") as! String)"
        }
    })

    // Do any additional setup after loading the view, typically from a nib.

}

func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {

    let location = locations.last

    let center = CLLocationCoordinate2D(latitude: location!.coordinate.latitude, longitude: location!.coordinate.longitude)

    let region = MKCoordinateRegion(center: center, span: MKCoordinateSpan(latitudeDelta: 1, longitudeDelta: 1))

    self.homeMap.setRegion(region, animated: true)

    self.locationManager.stopUpdatingLocation()

    self.homeMap.showsUserLocation = true

    locationCurrent = (manager.location)!

}

func locationManager(manager: CLLocationManager, didFailWithError error: NSError) {
    print("Errors: " + error.localizedDescription)
}

func loadTasks() {

    var title: String?
    var id: String?
    var distance: Double?

    var locationDict: [String:CLLocation] = [:]
    var refHandle = self.ref.child("tasks").observeEventType(FIRDataEventType.Value, withBlock: { (snapshot) in
        let tasksDict = snapshot.value as? NSDictionary
        for i in 0 ..< tasksDict!.count {
            let taskId = tasksDict!.allKeys[i] as! String
            print (taskId)
            id = taskId
            let task = tasksDict!.objectForKey(taskId) as! NSDictionary
            print (task)
            let lat = task.objectForKey("latitude") as! String
            let long = task.objectForKey("longitude") as! String
            title = task.objectForKey("title") as? String
            let latNum = Double(lat)! as CLLocationDegrees
            let longNum = Double(long)! as CLLocationDegrees
            print (latNum)
            print (longNum)
            let pointCoordinates: CLLocationCoordinate2D = CLLocationCoordinate2DMake(latNum, longNum)
            let pointLocation = CLLocation()
            pointLocation.dynamicType.init(latitude: latNum, longitude: longNum)
            locationDict[taskId] = pointLocation
            print("yes")

            if (self.locationCurrent!.distanceFromLocation(pointLocation) < 1000000000) {
                distance = self.locationCurrent!.distanceFromLocation(pointLocation)
                var task = Task(title: title, id: id, distance: distance)
                self.tasks += [task]
                print("yes yes")
                print (task._title)
            }
        }

    })

}

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

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

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier(cellIdentifier, forIndexPath: indexPath) as! TaskTableViewCell
    cell.titleLabel.text! = tasks[indexPath.row]._title!
    cell.distanceLabel.text! = "\(tasks[indexPath.row]._distance) m away"

    return cell
}
}

Yet when I run the app, the cells do not appear in the table view:

I've researched multiple tutorials and made sure that everything is entered correctly and connected in the storyboard. What's going on? Thanks so much for your help.

Answer 1

You need to call taskTable.reloadData() after your for loop that gets the tasks. If that function takes a while to run, you might want to call taskTable.reloadData() in the loop after you add each task so they can see the table populating.

A table view loads data in when the viewController that is its datasource first loads. Every time it's data changes, reloadData() must be called for it to run through the function cellForRowAtIndexPath again for each cell. There are ways to do this for individual cells, but that is not necessary for most situations. (Mainly when you have ridiculous amounts of work per whole table view reload to where you notice device lag)