When I try to customise a tableView cell, I found this error.
"Get output frames failed, state 8196"
I just have no idea it is the error from realm or from my customise tableView cell.
class StudentTableViewController: UITableViewController {
let realm = try! Realm()
var student: Results<StudentName>?
var selectedClass: ClassName? {
didSet {
load()
}
}
var selected: String = ""
override func viewDidLoad() {
super.viewDidLoad()
navigationController?.title = selected
tableView.register(StudentTableViewCell.self, forCellReuseIdentifier: "studentName")
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return student?.count ?? 1
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "studentName", for: indexPath) as! StudentTableViewCell
cell.name.text = student?[indexPath.row].name ?? "There are no student in this class"
cell.number.text = "\(student?[indexPath.row].studentNumber ?? 0)"
return cell
}
func load() {
student = selectedClass?.studentNames.sorted(byKeyPath: "studentNumber", ascending: true)
tableView.reloadData()
}
}
I think it did work when I am using Xcode 9 and Swift 4.1 but now in Xcode 10 it doesn't since it only show me this error and whole blank page of table view.
This error can be printed in the console when you use Realm even when you intend to only use it offline.
When the app is run in debug mode it will anonymously collect analytics, as stated in this answer: Realm Swift use locally only, however it still tries to connect online
To stop the error, click edit scheme, and add the environment variable REALM_DISABLE_ANALYTICS, and set it to YES as shown:
Environment variable screen
If you are using a Storyboard, you should not call tableView.register, you should simply set the reuseIdentifier for your prototype cell in storyboard.
If you have a separate .xib file for the cell, you should use:
tableView.register(nib: UINib?, forCellReuseIdentifier: String)
In other words the registration of your cell would be something like that:
self.tableView.register(UINib(nibName: "your cell nib name", bundle: nil), forCellReuseIdentifier: "your cell identifier")
If you have placed your cell in the tableview inside the controller that sits in the Storyboard then you do not need to register your cell, and as #Dávid Pásztor mentioned make sure you add the cell identifier to the cell in the Storyboard
Related
I am new to SWIFT and trying to show some data into table view controller but when I press the button it shows the above error. Please correct me
import UIKit
var selectedPlace : Place!
class ShowPlaceTableTableViewController: UITableViewController {
var places : [Place]!
override func viewDidLoad()
{
super.viewDidLoad()
places = readPlaces()
}
// MARK: - Table view data source
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of rows
return places.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! PlaceTableViewCell
cell.countryLabel.text = places[indexPath.row].country
cell.placeImageView.image = places[indexPath.row].picture
return cell
}
func readPlaces() -> [Place]
{
if UserDefaults.standard.object(forKey: "places") != nil
{
var data = UserDefaults.standard.object(forKey: "places") as! Data
let places = try! NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(data) as! [Place]
return places
}else
{
return [Place]()
}
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
selectedPlace = places[indexPath.row]
performSegue(withIdentifier: "detailSegue", sender: self)
}
}
Is your PlaceTableViewCell inside it's own xib separately OR is it inside the storyboard itself? You must register either a cell class or a nib before you try to dequeue the cell from tableView.
If it's inside the storyboard, then you can register the subclass to work with it.
tableView.register(PlaceTableViewCell.self, forCellReuseIdentifier: "PlaceTableViewCell")
If it's inside it's own xib separately, then you can register the UINib to work with it.
tableView.register(UINib(nibName: "PlaceTableViewCell", bundle: nil), forCellReuseIdentifier: "PlaceTableViewCell")
These need to be called once only, you can place these calls inside viewDidLoad().
Now you can dequeue it like following -
let cell = tableView.dequeueReusableCell(withIdentifier: "PlaceTableViewCell") as! PlaceTableViewCell
Note : The reuseIdentifier must be same in following places -
storyboard (or xib)
at the time of registration tableView.register...
at the time of dequeue tableView.dequeue...
I have a table, I want to make it so that when I click on a cell, the activity indicator spins around it, and not somewhere in an incomprehensible place
It looks like this. In the code, I have the MainViewController module and the Presenter module which determines when to start the activity indicator. I have an outlet
#IBOutlet weak var activity: UIActivityIndicatorView! = UIActivityIndicatorView(style: .gray)
I have two functions in the view controller that start the animation and stop
func startActivity() {
activity.startAnimating()
}
func stopActivity() {
activity.stopAnimating()
}
there is a function that handles a click on a cell
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: true)
output.callFromThePresenter(array: array[indexPath.row])
}
This function is implemented in the presenter.
func callFromThePresenter(array: String) {
let userInteractiveQueue = DispatchQueue.global(qos: .userInteractive)
async {
DispatchQueue.main.async {
self.view.startActivity()
}
userInteractiveQueue.async {
self.interactor.functionFromInteractor(data: array)
}
}
}
as I assumed, in the view controller, when you click on a cell, the callFromThePresenter () function will work, and the animation function and the data transfer function in the Interactor will start in it, as soon as the Interactor has completed this function, it will return the data to the Presenter and inside the call back function, I will run the stopActivity () function. And it worked until I decided to set the positioning
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: true)
output.callFromThePresenter(array: array[indexPath.row])
let cell = tableView.cellForRow(at: indexPath)
cell?.accessoryView = self.activity
}
as soon as i added these two lines
let cell = tableView.cellForRow(at: indexPath)
cell?.accessoryView = self.activity
I broke everything, as if I started up, I click on the table cell and the wheel turns where it is needed and everything works, but after receiving the result, I poke at some cell again, the whole program hangs, and I don’t know for what reason . At the same time, the functions work out how much I can understand it, because it comes to the console that the function was launched and got some result, but then the whole UI hangs tight and I can't do anything
Simple example:
In Interface Builder set the Style of the table view cell to custom.
Drag a label and an activity indicator into the cell and set appropriate constraints if needed.
Select the activity indicator, press ⌘⌥4 (Attributes Inspector) and check Hides When Stopped.
Create a custom class, a subclass of UITableViewCell in the project
class TitleCell: UITableViewCell {
#IBOutlet weak var titleLabel: UILabel!
#IBOutlet weak var activity: UIActivityIndicatorView!
var isRunning : Bool = false {
didSet {
isRunning ? activity.startAnimating() : activity.stopAnimating()
}
}
}
Set the class of the prototype cell in Interface Builder to TitleCell and connect the label and the indicator to the IBOutlets
Create a data model with at least a title and a isRunning property.
struct Model {
let title: String
var isRunning : Bool
}
Declare a data source array
var items = [Model]()
In cellForRow update the UI elements (replace the identifier with your real identifier)
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! TitleCell
let item = items[indexPath.row]
cell.titleLabel!.text = item.title
cell.isRunning = item.isRunning
return cell
}
To start and stop the indicator implement didSelectRow
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: false)
items[indexPath.row].isRunning.toggle()
tableView.reloadRows(at: [indexPath], with: .none)
}
To change the state of the indicator use always the pattern to set isRunning in the model and reload the row.
I think lazy var {}() should run once. But today I meet this problem troubles me. And I have on any thought. I'm crying.
Here is reproduction class:
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
private lazy var hotStockTableView: UITableView = {
let tableView = UITableView()
print("hotStockTableView ======> \(tableView) \n")
tableView.delegate = self
tableView.dataSource = self
// Here cause crash.
tableView.tableFooterView = UIView() // if comment this line, everthing is ok.
tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
return tableView
}()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(hotStockTableView)
hotStockTableView.frame = view.bounds
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
print("tableView =====> \(tableView) \n")
if tableView == hotStockTableView {
return 5
} else {
return 0
}
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
var cell = tableView.dequeueReusableCell(withIdentifier: "cell")
if cell == nil {
cell = UITableViewCell(style: .default, reuseIdentifier: "cell")
}
cell?.textLabel?.text = "\(indexPath.row)"
return cell!
}
}
Could someone help me?
The problem is that your closure to create a table view ends up being recursive.
When you set a tableFooterView on the table, it immediately tries to find out if that footer should be drawn / visible / onscreen immediately.
To know if the footer should be visible, the table view has to find out how many rows should currently be displayed, so it asks the data source (your view controller) for the number of rows in the the first section
Inside your method tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int, you have the line if tableView == hotStockTableView {. This tries to access the lazy hotStockTableView var, which still hasn't completed initializing, since that closure is what is calling this code in the first place
So the lazy var closure is kicked off again and recursively goes through the same steps over and over and over until stack overflow and crash.
Fortunately, the solution is easy. If you haven't set the data source yet then adding the table view footer will never call your number of rows data source method. So just change the order of code in your lazy closure to the following:
private lazy var hotStockTableView: UITableView = {
let tableView = UITableView()
print("hotStockTableView ======> \(tableView) \n")
tableView.tableFooterView = UIView()
tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
tableView.delegate = self
tableView.dataSource = self
return tableView
}()
Now your code will work just fine.
About lazy variables there is a good answer on SO:
As far as thread safety is concerned, lazy var are not thread safe
in Swift.
That means if two different threads try to access the same lazy var
at the same time, before such variable has been initialized it is
possible that one of the threads will access partially constructed
instance.
I'd suggest trying to set delegate and dataSource after the lazy view is created. It might be accessed by delegate or dataSource before it is fully initialized.
The problem I'm facing is probably some lack of understanding on the concept of reusable cells. I have, let's say, 30 rows to be created and each of them has a UISwitch.
When I toggle one of the switches, it's behavior should affect the other 29. The point is: as far as I know, iOS doesn't create all of them at once, but rather wait to reuse the cells when the TableView is scrolled up and down.
How can I keep a copy of those reused objects and tell iOS to set the proper value to the switches?
I've thought on having the cells appended to a [UISwitch] but I can't manage to have all the 30 cells in there, look:
...
var switches = [UISwitch]()
...
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Field10Cell", for: indexPath) as! Field10TableViewCell
...
//cell.value is a UISwitch
if !switches.contains(cell.value) {
switches.append(cell.value)
}
return cell
}
You could create a set which stores the indexes of the cells whose switches have been pressed.
var activeSwitches = Set<IndexPath>()
Whenever a user presses the switch on a cell, you store it on the set like this:
activeSwitches.insert(indexPath)
If you need to check if a switch was activated, just check if its container cell's indexPath is in active switches like so:
if activeSwitches.contains(indexPath) {
// do something
}
In order to know when a user pressed a specific switch I recommend the folliwing:
In cellForRowAtIndexPath save the current indexPath into your Field10TableViewCell.
Create a protocol on Field10TableViewCell and add a delegate.
protocol Field10Delegate {
func didChangeSwitch(value: Bool, indexPath: IndexPath)
}
class Field10TableViewCell {
var delegate: Field10Delegate?
var indexPath: IndexPath?
#IBOutlet weak var fieldSwitch: UISwitch! // Can't use 'switch' as a variable name
#IBAction func switchValueChanged(_ sender: UISwitch) {
if let indexPath = indexPath {
delegate?.didChangeSwitch(value: sender.isOn, indexPath: indexPath)
}
}
When you create a cell, set the view controller as a delegate
let cell = tableView.dequeueReusableCell(withIdentifier: "Field10Cell", for: indexPath) as! Field10TableViewCell
cell.delegate = self
cell.indexPath = indexPath
Make your view controller comply with the protocol:
extension ViewController: Field10Delegate {
/* Whenever a switch is pressed on any cell, this delegate will
be called. This is a good place also to trigger a update to
your UI if it has to respond to switch changes.
*/
func didChangeSwitch(value: Bool, indexPath: IndexPath) {
if value {
activeSwitches.insert(indexPath)
} else {
activeSwitches.remove(indexPath)
}
updateUI()
}
}
With the above, at any point you will know which switches are active or not and you can process the dequeued cells with this information.
I have an app that has a custom button in a custom cell. If you select the cell it segues to the a detail view, which is perfect. If I select a button in a cell, the code below prints the cell index into the console.
I need to access the contents of the selected cell (Using the button) and add them to an array or dictionary. I am new to this so struggling to find out how to access the contents of the cell. I tried using didselectrowatindexpath, but I don't know how to force the index to be that of the tag...
So basically, if there are 3 cells with 'Dog', 'Cat', 'Bird' as the cell.repeatLabel.text in each cell and I select the buttons in the rows 1 and 3 (Index 0 and 2), it should add 'Dog' and 'Bird' to the array/dictionary.
// MARK: - Table View
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return postsCollection.count
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell: CustomCell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as! CustomCell
// Configure the cell...
var currentRepeat = postsCollection[indexPath.row]
cell.repeatLabel?.text = currentRepeat.product
cell.repeatCount?.text = "Repeat: " + String(currentRepeat.currentrepeat) + " of " + String(currentRepeat.totalrepeat)
cell.accessoryType = UITableViewCellAccessoryType.DetailDisclosureButton
cell.checkButton.tag = indexPath.row;
cell.checkButton.addTarget(self, action: Selector("selectItem:"), forControlEvents: UIControlEvents.TouchUpInside)
return cell
}
func selectItem(sender:UIButton){
println("Selected item in row \(sender.tag)")
}
OPTION 1. Handling it with delegation
The right way of handling events fired from your cell's subviews is to use delegation.
So you can follow the steps:
1. Above your class definition write a protocol with a single instance method inside your custom cell:
protocol CustomCellDelegate {
func cellButtonTapped(cell: CustomCell)
}
2. Inside your class definition declare a delegate variable and call the protocol method on the delegate:
var delegate: CustomCellDelegate?
#IBAction func buttonTapped(sender: AnyObject) {
delegate?.cellButtonTapped(self)
}
3. Conform to the CustomCellDelegate in the class where your table view is:
class ViewController: CustomCellDelegate
4. Set your cell's delegate
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as CustomCell
cell.delegate = self
return cell
}
5. Implement the required method in your view controller class.
EDIT: First define an empty array and then modify it like this:
private var selectedItems = [String]()
func cellButtonTapped(cell: CustomCell) {
let indexPath = self.tableView.indexPathForRowAtPoint(cell.center)!
let selectedItem = items[indexPath.row]
if let selectedItemIndex = find(selectedItems, selectedItem) {
selectedItems.removeAtIndex(selectedItemIndex)
} else {
selectedItems.append(selectedItem)
}
}
where items is an array defined in my view controller:
private let items = ["Dog", "Cat", "Elephant", "Fox", "Ant", "Dolphin", "Donkey", "Horse", "Frog", "Cow", "Goose", "Turtle", "Sheep"]
OPTION 2. Handling it using closures
I've decided to come back and show you another way of handling these type of situations. Using a closure in this case will result in less code and you'll achieve your goal.
1. Declare a closure variable inside your cell class:
var tapped: ((CustomCell) -> Void)?
2. Invoke the closure inside your button handler.
#IBAction func buttonTapped(sender: AnyObject) {
tapped?(self)
}
3. In tableView(_:cellForRowAtIndexPath:) in the containing view controller class :
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! CustomCell
cell.tapped = { [unowned self] (selectedCell) -> Void in
let path = tableView.indexPathForRowAtPoint(selectedCell.center)!
let selectedItem = self.items[path.row]
println("the selected item is \(selectedItem)")
}
Since you have 1 section in the table view you can get the cell object as below.
let indexPath = NSIndexPath(forRow: tag, inSection: 0)
let cell = tableView.cellForRowAtIndexPath(indexPath) as! CustomCell!
where tag you will get from button tag.
Swift 3
I just get solution for access cell in #IBAction function using superview of button tag.
let cell = sender.superview?.superview as! ProductCell
var intQty = Int(cell.txtQty.text!);
intQty = intQty! + 1
let strQty = String(describing: intQty!);
cell.txtQty.text = strQty
#IBAction func buttonTap(sender: UIButton) {
let button = sender as UIButton
let indexPath = self.tableView.indexPathForRowAtPoint(sender.center)!
}
I updated option 1 of the answer from Vasil Garov for Swift 3
1. Create a protocol for your CustomCell:
protocol CustomCellDelegate {
func cellButtonTapped(cell: CustomCell)
}
2. For your TableViewCell declare a delegate variable and call the protocol method on it:
var delegate: CustomCellDelegate?
#IBAction func buttonTapped(sender: AnyObject) {
delegate?.cellButtonTapped(self)
}
3. Conform to the CustomCellDelegate in the class where your tableView is:
class ViewController: CustomCellDelegate
4. Set your cell's delegate
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as CustomCell
cell.delegate = self
return cell
}
5. Implement the required method in your ViewController.
Based on Cao's answer, here is a solution to handle buttons in a collection view cell.
#IBAction func actionButton(sender: UIButton) {
let point = collectionView.convertPoint(sender.center, fromView: sender.superview)
let indexPath = collectionView.indexPathForItemAtPoint(point)
}
Be aware that the convertPoint() function call will translate the button point coordinates in the collection view space. Without, indexPath will always refer to the same cell number 0
XCODE 8: Important Note
Do not forget to set the tags to a different value than 0.
If you attempt to cast an object with tag = 0 it might work but in some weird cases it doesn't.
The fix is to set the tags to different values.
Hope it helps someone.