UITableviewCell text disappears after a blink on every reload - ios

Reload is not calling cellForRowAt whenever I am trying to reload without the main thread closure. This is my code:
class UtititySwitcher:NSObject, UITableViewDataSource, UITableViewDelegate {
let utilityTableview = UITableView()
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 3
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: .default, reuseIdentifier: "Mycell")
cell.textLabel?.text = "hello"
return cell
}
func Open(loginID:String, view:UIView)
{
let frm = view.bounds
let backView = UIView(frame: frm)
self.utilityTableview.frame = CGRect(x: frm.minX + 10, y: frm.midY - 50, width: frm.width - 20, height: 100)
self.utilityTableview.backgroundColor = UIColor.white
self.utilityTableview.delegate = self
self.utilityTableview.dataSource = self
backView.addSubview(self.utilityTableview)
view.addSubview(backView)
OperationQueue.main.addOperation {
self.utilityTableview.reloadData()
}
}
}


You haven't set the delegate and data source for the utilityTableview so this table view is not informed who shall it listen to and take data from. At the class init, add utilityTableview.delegate = self and utilityTableview.dataSource = self


I think the reason is :
the OperationQueue have not init
you can try:
let operationQueue = OperationQueue()
operationQueue.main.addOperation {
self.utilityTableview.reloadData
}

Related

UITableViewCell from Xib, cell hight and cell selection area

I have a UITableViewController, which has a custom cell that I want to display an image and labels. screenshots can explain my problem very well, it looks like this
.
And when I select any cell it looks like
In tableviewcontroller cell is not visible in proper shape according to constraints
here is my custom cell with autolayout constraints
How I can fix this issue? ... I created this tableviewcontroller programmatically without using storyboard.
here is code sample of data source and delegates of tableviewcontroller
override func numberOfSections(in tableView: UITableView) -> Int {
var numOfSections: Int = 0
let count = conversations.count
if count > 0 {
// tableView.separatorStyle = .none
numOfSections = 1
tableView.backgroundView = nil
}
else
{
let frame = CGRect(x: 0,
y: 0,
width: tableView.bounds.size.width,
height: tableView.bounds.size.height)
let noDataLabel: UILabel = UILabel(frame: frame)
noDataLabel.text = "You don't have any messages. 🙃"
noDataLabel.textColor = UIColor.black
noDataLabel.textAlignment = .center
tableView.backgroundView = noDataLabel
tableView.separatorStyle = .none
}
return numOfSections
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return conversations.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "inboxCell", for: indexPath) as! InboxCell
cell.conversation = conversations[indexPath.row]
return cell
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let uids = conversations[indexPath.row].conversationUseruids
for uid in uids{
if uid == Account.account.user.uid{
}
else{
User.getUser(with: uid, completion: { (user) in
self.selectedUser.append(user!)
})
}
}
tableView.deselectRow(at: indexPath, animated: true)
let index = indexPath.row as Int
messageVC.conversationIndex = index
messageVC.conversation = self.conversations[index]
navigationController?.pushViewController(messageVC, animated: true)
}
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 80
}

it happen because your image not have upper lower constraint if not working than let me know

reloadData() calls cellForRowAtIndexPath for every cell

So I'm having this issue that when reloadData() is called after the initial API call, it calls willDisplayCell method which when the last cell is displayed will load more data (API returns 10 data at a time).
However in the view it can show only 4 - 5 cells as I set the row height to 175 points manually. Does anyone know why is this happening?
If this is how the tableView works what can I do to make my tableView to load only 10 initially?
Following is my code.
class MainViewController: UIViewController {
var tableView: UITableView!
var photoViewmodel: PhotoViewModel!
override func viewDidLoad() {
super.viewDidLoad()
self.title = "Home"
initTableView()
photoViewmodel = PhotoViewModel()
photoViewmodel.loadNewPhotos {
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
}
func initTableView() {
tableView = UITableView.init(frame: self.view.frame, style: .plain)
tableView.delegate = self
tableView.dataSource = self
tableView.rowHeight = 175
tableView.separatorStyle = .none
tableView.register(HomeTableViewCell.nib, forCellReuseIdentifier: HomeTableViewCell.identifier)
view.addSubview(tableView)
}
}
extension MainViewController: UITableViewDataSource, UITableViewDelegate {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return photoViewmodel.photos.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
print("cellForRowAt")
let cell = tableView.dequeueReusableCell(withIdentifier: HomeTableViewCell.identifier, for: indexPath) as! HomeTableViewCell
cell.tag = indexPath.row
cell.configureCell(url: photoViewmodel.photos[indexPath.row].regularImgUrl, cacheKey: indexPath.row)
return cell
}
func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
print("willDisplay")
let lastCell = photoViewmodel.photos.count - 1
if indexPath.row == lastCell {
print("add 10 more photos")
photoViewmodel.loadNewPhotos(
DispatchQueue.main.async {
self.tableView.reloadData()
}
})
}
}
}

How do I get correct animation behavior of cell height change when placing UITableView's beginUpdates() & endUpdates() inside animation block

So I want to change the default animation duration of UITableView's beginUpdates() & endUpdates(), which I think is 0.3s.
I tried placing them inside a UIView animation block, then I got abrupt animation.
To see what I am talking about, create a new iOS "Single View Application" Project, and replace ViewController.swift with the following code:
class ViewController: UIViewController {
var tableView = UITableView()
var isExpanded = false
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(tableView)
tableView.frame = view.bounds
tableView.dataSource = self
tableView.delegate = self
let changeHeightButton = UIBarButtonItem(title: "Change Height", style: .plain, target: self, action: #selector(changeHeight))
navigationItem.rightBarButtonItem = changeHeightButton
}
func changeHeight() {
isExpanded = !isExpanded
UIView.animate(withDuration: 0.5, animations: {
self.tableView.beginUpdates()
self.tableView.endUpdates()
}, completion: nil)
}
}
extension ViewController: UITableViewDataSource, UITableViewDelegate {
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell") ?? UITableViewCell(style: .default, reuseIdentifier: "cell")
cell.textLabel?.text = "Section \(indexPath.section), Row \(indexPath.row)"
return cell
}
func numberOfSections(in tableView: UITableView) -> Int{
return 4
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 3
}
func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
return "Section: \(String(section))"
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
if isExpanded && indexPath == IndexPath(row: 0, section: 0) { return 300 }
else { return 44 }
}
}

didSelectRowAtIndexPath not working, Swift 3

Can anyone see why in the world didSelectRowAtIndexPath would not be called? I have triple checked by delegate both in the code and in storyboard.
class AddCard: UIViewController,UIPopoverPresentationControllerDelegate, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var cardView: UIView!
#IBOutlet weak var tableView: UITableView!
let tableItems = ["Background Color","Background Image","Font Style","Font Color"]
let cellID = "cell"
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func setBackgroundColor (_ color: UIColor) {
cardView.backgroundColor = color
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return tableItems.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellID, for: indexPath as IndexPath)
let row = indexPath.row
cell.textLabel?.text = tableItems[row]
return cell
}
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: IndexPath) {
tableView.deselectRow(at: indexPath as IndexPath, animated: true)
print(indexPath.row)
let row = indexPath.row
switch(row){
case 0:
let popoverVC = storyboard?.instantiateViewController(withIdentifier: "colorPickerVC") as! ColorPickerViewController
popoverVC.modalPresentationStyle = .popover
popoverVC.preferredContentSize = CGSize(width: 284, height: 446)
if let popoverController = popoverVC.popoverPresentationController {
popoverController.sourceView = self.view
popoverController.sourceRect = CGRect(x: 0, y: 0, width: 85, height: 30)
popoverController.permittedArrowDirections = .any
popoverController.delegate = self
popoverVC.delegate = self
}
present(popoverVC, animated: true, completion: nil)
break
default: break
}
}
}

Swift 3 modified the signature of the method (a lot of methods too, new "rules"/style)
Replace:
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: IndexPath) with
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath)
Notice the _, the didSelectRowAt vs didSelectRowAtIndexPath, like the other ones you updated (which adapted also the same "style"), but not this one.
Remove the line and let XCode do the autocompletion. Else, you can just replace it with the one from the doc.

Create UITableView programmatically in Swift

I try to implement UITableView programmatically without use of xib or Storyboards. This is my code:
ViewController.swift
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let table: UITableViewController = MyTableViewController()
let tableView: UITableView = UITableView()
tableView.frame = CGRect(x: 10, y: 10, width: 100, height: 500)
tableView.dataSource = table
tableView.delegate = table
self.view.addSubview(tableView)
}
}
MyTableViewController.swift
import UIKit
class MyTableViewController: UITableViewController {
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
NSLog("sections")
return 2
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
NSLog("rows")
return 3
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
NSLog("get cell")
let cell = UITableViewCell(style: UITableViewCellStyle.Value1, reuseIdentifier: "Cell")
cell.textLabel!.text = "foo"
return cell
}
}
But when I run app, all I get is empty table. In log I see a few lines of sections and rows, but no get cell. How can I fix this code to get table with 6 lines of foo text?

Note: As you mentioned you just started programming in Swift. I created a tableView programmatically. Copy and paste below code into your viewController and run the project...
import UIKit
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
private let myArray: NSArray = ["First","Second","Third"]
private var myTableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
let barHeight: CGFloat = UIApplication.shared.statusBarFrame.size.height
let displayWidth: CGFloat = self.view.frame.width
let displayHeight: CGFloat = self.view.frame.height
myTableView = UITableView(frame: CGRect(x: 0, y: barHeight, width: displayWidth, height: displayHeight - barHeight))
myTableView.register(UITableViewCell.self, forCellReuseIdentifier: "MyCell")
myTableView.dataSource = self
myTableView.delegate = self
self.view.addSubview(myTableView)
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
print("Num: \(indexPath.row)")
print("Value: \(myArray[indexPath.row])")
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return myArray.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath as IndexPath)
cell.textLabel!.text = "\(myArray[indexPath.row])"
return cell
}
}
Output:

Updated for Swift 3
Option 1:
import UIKit
//
// MARK :- TableViewController
//
class TableViewController: UITableViewController {
private let headerId = "headerId"
private let footerId = "footerId"
private let cellId = "cellId"
//
// MARK :- HEADER
//
override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return 150
}
override func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let header = tableView.dequeueReusableHeaderFooterView(withIdentifier: headerId) as! CustomTableViewHeader
return header
}
//
// MARK :- FOOTER
//
override func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
return 150
}
override func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? {
let footer = tableView.dequeueReusableHeaderFooterView(withIdentifier: footerId) as! CustomTableViewFooter
return footer
}
//
// MARK :- CELL
//
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 150
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) as! CustomTableCell
return cell
}
override func viewDidLoad() {
super.viewDidLoad()
title = "TableView Demo"
view.backgroundColor = .white
setupTableView()
}
func setupTableView() {
tableView.backgroundColor = .lightGray
tableView.register(CustomTableViewHeader.self, forHeaderFooterViewReuseIdentifier: headerId)
tableView.register(CustomTableViewFooter.self, forHeaderFooterViewReuseIdentifier: footerId)
tableView.register(CustomTableCell.self, forCellReuseIdentifier: cellId)
}
}
//
// MARK :- HEADER
//
class CustomTableViewHeader: UITableViewHeaderFooterView {
override init(reuseIdentifier: String?) {
super.init(reuseIdentifier: reuseIdentifier)
contentView.backgroundColor = .orange
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
//
// MARK :- FOOTER
//
class CustomTableViewFooter: UITableViewHeaderFooterView {
override init(reuseIdentifier: String?) {
super.init(reuseIdentifier: reuseIdentifier)
contentView.backgroundColor = .green
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
//
// MARK :- CELL
//
class CustomTableCell: UITableViewCell {
override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
contentView.backgroundColor = .white
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
Option 2: replace above Option 1 TableViewController with this class
import UIKit
//
// MARK :- ViewController
//
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
private let headerId = "headerId"
private let footerId = "footerId"
private let cellId = "cellId"
lazy var tableView: UITableView = {
let tv = UITableView(frame: .zero, style: .plain)
tv.translatesAutoresizingMaskIntoConstraints = false
tv.backgroundColor = .lightGray
tv.delegate = self
tv.dataSource = self
tv.register(CustomTableViewHeader.self, forHeaderFooterViewReuseIdentifier: self.headerId)
tv.register(CustomTableViewFooter.self, forHeaderFooterViewReuseIdentifier: self.footerId)
tv.register(CustomTableCell.self, forCellReuseIdentifier: self.cellId)
return tv
}()
//
// MARK :- HEADER
//
func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return 150
}
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let header = tableView.dequeueReusableHeaderFooterView(withIdentifier: headerId) as! CustomTableViewHeader
return header
}
//
// MARK :- FOOTER
//
func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
return 150
}
func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? {
let footer = tableView.dequeueReusableHeaderFooterView(withIdentifier: footerId) as! CustomTableViewFooter
return footer
}
//
// MARK :- CELL
//
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 150
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) as! CustomTableCell
return cell
}
override func viewDidLoad() {
super.viewDidLoad()
title = "TableView Demo"
view.backgroundColor = .white
view.addSubview(tableView)
setupAutoLayout()
}
func setupAutoLayout() {
tableView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
tableView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
tableView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
tableView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
}
}

Swift 4 compatible
Instead of adding a UITableView to your UIViewController, you should consider creating a UITableViewController and avoid setting up delegates:
class YourTVC: TableViewController {
override func viewDidLoad() {
super.viewDidLoad()
// setup custom cells if you use them
tableView.register(CustomTableViewCell.self, forCellReuseIdentifier: "yourCell")
}
// MARK: tableView
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 3 // set to value needed
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "yourCell", for: indexPath) as! CustomTableViewCell
cell.textLabel?.text = "Cell at row \(indexPath.row)"
return cell
}
}

It makes no sense that you are using a UITableViewController as the data source and delegate for your view controller's table view. Your own view controller should be the table view's data source and delegate.
Since you seem to want a view controller with a table view that doesn't take up the entire view, move every thing to your view controller as follows:
ViewController.swift:
import UIKit
class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
override func viewDidLoad() {
super.viewDidLoad()
let tableView: UITableView = UITableView()
tableView.frame = CGRect(x: 10, y: 10, width: 100, height: 500)
tableView.dataSource = self
tableView.delegate = self
self.view.addSubview(tableView)
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
NSLog("sections")
return 2
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
NSLog("rows")
return 3
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
NSLog("get cell")
let cell = UITableViewCell(style: UITableViewCellStyle.Value1, reuseIdentifier: "Cell")
cell.textLabel!.text = "foo"
return cell
}
}

You don't need to make a separate class for UITableView. Just in your ViewController class implement protocols of UITableViewDelegate and UITableViewDataSource and then implement delegate methods.
I think your code should be like
class ViewController: UIViewController , UITableViewDelegate , UITableViewDataSource {
override func viewDidLoad() {
super.viewDidLoad()
let table: UITableViewController = MyTableViewController()
let tableView: UITableView = UITableView()
tableView.frame = CGRect(x: 10, y: 10, width: 100, height: 500)
tableView.dataSource = table
tableView.delegate = table
self.view.addSubview(tableView)
}
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
NSLog("sections")
return 2
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
NSLog("rows")
return 3
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
NSLog("get cell")
let cell = UITableViewCell(style: UITableViewCellStyle.Value1, reuseIdentifier: "Cell")
cell.textLabel!.text = "foo"
return cell
}
}
Tell us more info or show logs if you still face issue.

I had a similar issue in that the data would not populate for my programmatic UITableView. This was because I was using a delegate/dataSource without a strong reference. Once I kept a reference to it (I had one class implementing both UITableViewDataSource and UITableViewDelegate), the data was populated.

import UIKit
class ViewController: UITableViewController {
override func viewDidLoad() {
super.viewDidLoad()
tableView.register(TableCell.self, forCellReuseIdentifier: "cell")
}
override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 10
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! TableCell
cell.nameLabel.text = "TableViewCell programtically"
cell.nameLabel.textAlignment = .center
cell.nameLabel.textColor = .white
return cell
}
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 100
}
}

Simple solution
import UIKit
class CustomTableViewController: UICollectionViewController {
override func viewDidLoad() {
super.viewDidLoad()
tableView.register(UITableViewCell.self, forCellReuseIdentifier: "Cell")
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 10
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath as IndexPath)
cell.textLabel!.text = "\(indexPath.row)"
return cell
}
}

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