Problem:
tableView Controller is not showing categoryArray items in table.
Diagnose:
- 1st tableView numberOfSections method is triggered and returns 1 (print(categoryArray.count)
- 2nd tableView cellForRowAt method never starts (print statement does not work)
- Table View Controller does not need delegate. However, I tried to add tableView.delegate = self
- x-code restart did not help
Question:
Why the 2nd tableView method does not work and how to fix this?
import UIKit
import CoreData
class CategoryViewController: UITableViewController {
var categoryArray = [Category]()
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
override func viewDidLoad() {
super.viewDidLoad()
loadCategories()
}
// MARK: - TableView DataSource Methods
override func numberOfSections(in tableView: UITableView) -> Int {
return categoryArray.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
print("this should print")
let cell = tableView.dequeueReusableCell(withIdentifier: "CategoryCell", for: indexPath) as! CategoryCell
let category = categoryArray[indexPath.row]
cell.categoryNameTextField.text = category.name
return cell
}
Instead of numberOfSections implement numberOfRows
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return categoryArray.count
}
At the end of viewDidLoad reload the table view
override func viewDidLoad() {
super.viewDidLoad()
loadCategories()
tableView.reloadData()
}
If loadCategories() contains something asynchronous reload the table view when the data are loaded.
Related
I do not understand why my cell is not showing up even though I have the correct identifier and class
class homeViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
print("p")
let cell: homeTableViewCell = tableView.dequeueReusableCell(withIdentifier: "homeTableViewCell", for: indexPath) as! homeTableViewCell
return cell
}
}
The identifier is the same in both table view cell and here
Please set delegate and dataSource for your tableview.
For ex:
this.tableView.delegate = self
this.tableView.dataSource = self
drug an outlet of your tableview and set a name. suppose the name you set myTableView . in viewDidLoad() write these 2 line of code.
myTableView.delegate = self
myTableView.dataSource = self
or in storyboard , press ctrl and drug your mouse with left clicking to the top header of storyboard view controller, then enable delegate and dataSource .
hope the problem will solve .
if you have any issue comment here.
i have a tableview in a viewcontroller and because i need to reuse most of the code for another table i created an extra class:
class StatisticsViewDelegate: NSObject, UITableViewDelegate, UITableViewDataSource {
var defaultList:[String]
var infolist:[String] = []
var tableView:UITableView
var controller:UIViewController?
init(defaultList:[String], view:UITableView, controller:UIViewController?) {
self.defaultList = defaultList
self.controller = controller
tableView = view
super.init()
tableView.delegate = self
tableView.dataSource = self
loadTable()
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return infolist.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "infocell", for: indexPath) as! TableViewCell
// [fill cell]
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
// [...]
}
func loadTable() {
DispatchQueue.global(qos: .userInitiated).async {
//[...]
// in this case:
self.infolist = self.defaultList
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
}
}
and in my UITViewController in the viewDidLoad():
delegate = StatisticsViewDelegate(defaultList: defaultList, view: tableView, controller:self)
delegate is a member of the ViewController
now when i run it, the function func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) never gets called. The func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) gets called however(before and after the reload) and returns the correct number(in my case 4). The TableView isn't visible at all. Where is my error?
Maybe you can use the subclassing strategy to resolve your problem. There are many reference passed to your class and if you forgot to clean that up you will be have memory leaks in your hand. So I'll suggest the simple example as below. You can modify as you like and let me know if that was what you are after. If not please pardon me.
//This will be parent class that will handle all table methods, so you need to write only once the delegates and stuffs
class MyCommonTableController: UITableViewController {
var infoList = [String]()
// MARK: - TableView Delegate and Datsource Impl
override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return infoList.count
}
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 55.0
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
cell.textLabel?.text = infoList[indexPath.row]
return cell
}
}
The first class that is directly subclassing the from above MyCommonTableController
//In here we just have to know the data and set the infoList from parent
class TheTableViewController: MyCommonTableController {
let defaultList = ["Data1","Data2","Data3"] //....etc
override func viewDidLoad() {
super.viewDidLoad()
//this is were I will set those
infoList = defaultList
//reload the table
tableView.reloadData()
}
}
The second class that is directly subclassing the from above MyCommonTableController. Same process goes here
class TheSecondTableViewController: MyCommonTableController {
let defaultList = ["List1","List2","List3"] //....etc
override func viewDidLoad() {
super.viewDidLoad()
//this is were I will set those
infoList = defaultList
//reload the table
tableView.reloadData()
}
}
And now you are not repeating and table methods. You can also get the reference of table and use in your norma table view
#IBOutlet weak var theTable: UITableView!
let defaultList = ["List1","List2","List3"] //....etc
let commonTable = MyCommonTableController()
// MARK: - LifeCycle
override func viewDidLoad() {
super.viewDidLoad()
commonTable.infoList = defaultList
commonTable.tableView = theTable
}
I've made an app using a table view to persist data. The table view shows the elements of an array which is saved through UserDefaults. Since TableViewControllers look kind of ugly, I did it a bit different: I put a TableView into a normal ViewController.
My problem is: even though I did everything I could to get the TableView to show the data, it doesn't, and I don't know why. Could anyone help me?
Here's the code of the ViewController:
class ErfolgreicheChallenges: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet var myTableView: UITableView!
var data = [String]()
override func viewDidLoad() {
super.viewDidLoad()
myTableView.delegate = self
data.append("test")
data.append("lol")
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 10
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
myTableView.dataSource = self
let cell = myTableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
cell.textLabel!.text = data[indexPath.row]
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
}
}
Thanks to everyone for having a look! Have a great day
Replace viewDidLoad with
override func viewDidLoad() {
super.viewDidLoad()
myTableView.dataSource = self
myTableView.delegate = self
data.append("test")
data.append("lol")
myTableView.reloadData()
}
and replace numberOfRowsInSection with
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return data.count
}
and delete myTableView.dataSource = self in cellForRow.
If the code is crashing then myTableView is not connected in IB.
As mentioned in the comments, consider to use UITableViewController which got a table view instance with pre-connected data source and delegate.
You need to set the data source and data delegate in viewDidLoad, or somewhere similar.
You are setting the datasource inside cellForRowAt, but that will never be called!
I have a tableview that is added programatically below that I want to hook up the delegate and dataSource to an external class. The code looks right however the tableview gets added to the view without getting the cell layout from the external class.
let tableView: UITableView = {
let dataService = ActivityDataService()
let tb = UITableView()
tb.tableHeaderView = nil
tb.tableFooterView = nil
tb.rowHeight = 50
tb.estimatedRowHeight = 50
tb.dataSource = dataService
tb.delegate = dataService
tb.register(ProfileActivitySubCell.self, forCellReuseIdentifier: "tableCell")
return tb
}()
Here is the activity service class:
class ActivityDataService: NSObject, UITableViewDelegate, UITableViewDataSource {
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 4
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "tableCell", for: indexPath) as! ProfileActivitySubCell
return cell
}
func tableView(_ tableView: UITableView, estimatedHeightForHeaderInSection section: Int) -> CGFloat {
return 0
}
func tableView(_ tableView: UITableView, estimatedHeightForRowAt indexPath: IndexPath) -> CGFloat {
return 50
}
}
Thanks
When using a UITableView thats not in a storyboard or similar you need to register the cell with an identifier.
Depending on your UITableViewCell (if its a subclass and/or if you are using nibs or not)
You could use one of these methods:
open func register(_ nib: UINib?, forCellReuseIdentifier identifier: String)
open func register(_ cellClass: Swift.AnyClass?, forCellReuseIdentifier identifier: String)
Which is methods of UITableView
In your case probably something like this:
tb.register(ProfileActivitySubCell.classForCoder(), forCellReuseIdentifier: "tableCell")
1) Refactor the table view data source methods to a separate class
class IceCreamListDataSource: NSObject, UITableViewDataSource
{
// MARK: - Table view data source
func numberOfSectionsInTableView(tableView: UITableView) -> Int
{
return 1
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
return 5
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
{
let cell = tableView.dequeueReusableCellWithIdentifier("IceCreamListCell", forIndexPath: indexPath)
return cell
}
}
2) In your controller class do this-:
class IceCreamListViewController: UITableViewController
{
let dataSource = IceCreamListDataSource()
// MARK: - View lifecycle
override func viewDidLoad()
{
super.viewDidLoad()
tableView.dataSource = dataSource
}
}
I managed to solve the issue. As the tableView was inside a collection view I had to use a storyboard object outlet. Finally inside the collection view cell I had to set the delegate and dataSource to the newly created object.
cell.tableView.dataSource = dataService
cell.tableView.delegate = dataService
This is a fairly simple question I think. I've separated my UITableView delegate / data sources into their own extensions
//MARK: - UITableView Data Source/Delegate
extension TweetsViewController: UITableViewDataSource {
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 0
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell") as! TweetCell
return cell
}
}
However in the view controller itself I need to set the tblView delegate
class TweetsViewController : UIViewController {
#IBOutlet weak var tblView: UITableView!
var fetchedResultsController : NSFetchedResultsController!
//MARK: View Management
override func viewDidLoad() {
super.viewDidLoad()
tblView.dataSource = self
}
}
However, since the view controller is nor conforming to the protocols but having the extensions handle them, then how do I explicitly set the datasource and delegate for the tableView? Thanks!
You can divide in a extension, as you can check in the apple documentation section about Extensions handling Protocols.
Here I have implement a minimum code doing what you ask, check it out.
import UIKit
class TableViewViewController: UIViewController {
#IBOutlet weak var table: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
table.delegate = self
table.dataSource = self
}
}
extension TableViewViewController: UITableViewDelegate,UITableViewDataSource {
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("reuseIdentifier", forIndexPath: indexPath)
cell.textLabel!.text = "it works"
return cell
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
}
In Swift 3 and above the table view datasource and delegate methods changed.
import UIKit
class HomeViewController: UIViewController {
#IBOutlet var tblPropertyList: UITableView!
// MARK: - View Life Cycle
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
tblPropertyList.delegate = self
tblPropertyList.dataSource = self
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
// MARK: - Table View DataSource
extension HomeViewController: UITableViewDataSource {
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "reuseIdentifier", for: indexPath as IndexPath)
cell.textLabel!.text = "\(indexPath.row) - Its working"
return cell
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 2
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 2
}
}
// MARK: - Table View Delegate
extension HomeViewController: UITableViewDelegate {
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let indexPath = tableView.indexPathForSelectedRow
let currentCell = tableView.cellForRow(at: indexPath!)!
print(currentCell.textLabel!.text!)
}
}
the view controller is nor conforming to the protocols but having the extensions handle them
This is incorrect. The extension makes the view controller conformant to the protocols, and the data source and delegate can be set as usual, e.g.: self.tableView.delegate = self
Now in Swift 5.1 you don't need to inherit UITableViewDelegate and UITableViewDataSource
extension HomeViewController {
// MARK: - Table View DataSource
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "reuseIdentifier", for: indexPath as IndexPath)
cell.textLabel!.text = "\(indexPath.row) - Its working"
return cell
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 2
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 2
}
}
// MARK: - Table View Delegate
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let indexPath = tableView.indexPathForSelectedRow
let currentCell = tableView.cellForRow(at: indexPath!)!
print(currentCell.textLabel!.text!)
}
}