I created a tableview with a custom cell.
Inside my UITableViewCell file I have the following code :
var myTipView:EasyTipView?
#IBAction func infoBtn_pressed(_ sender: UIButton) {
//print(diseases)
if self.myTipView == nil
{
self.myTipView = EasyTipView(text: diseases, preferences: EasyTipView.globalPreferences)
self.myTipView!.show(forView: sender)
}
else
{
self.myTipView!.dismiss()
self.myTipView = nil
}
}
and inside my UIViewController I have a tableview with the code :
var myTipView:EasyTipView?
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = myTable.dequeueReusableCell(withIdentifier: "diffCell") as! diffCell
cell.myTipView = self.myTipView
}
the when I tried to use the value of self.myTipView I found it nil and this is obvious because it have no value until the infoBtn_pressed is activated and in this case cell.myTipView is always nil when the table first created
how can i get self.myTipView to have the value after the button is pressed to use it inside UIViewController
Once you set the myTipView value, You need to refresh the table by doing this :-
tableView.reloadData()
You could try adding an observer to your myTipView parameter:
var myTipView : EasyTipView? {
didSet {
// Test that myTipView is non-nil
if let _ = myTipView {
// implement a function here that updates the cells in the table view...
}
}
}
I'm assuming you can handle updating the table cells (incidentally, your implementation seems to suggest that every cell has the same EasyTipView property: is that your intention?). Hope that helps.
Finally i used delegates to notify the table when a button is clicked in the table cell and worked great (^^)
Related
I have a table view controller with a custom cell which contains a text field - it's a form basically.
i want to automatically go to the next text field when users press "return" on their keyboard but for some reason my solution doesn't work.
In TableViewController, I do:
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as? CustomCell
cell?.box.tag = indexPath.row
In my custom table view cell, I have
override func awakeFromNib() {
super.awakeFromNib()
box.delegate = self
...
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
if let nextField = textField.superview?.viewWithTag(textField.tag+1) as? UITextField {
nextField.becomeFirstResponder()
} else {
textField.resignFirstResponder()
}
return true
}
The issue is that textField.superview?.viewWithTag(textField.tag+1) is always nil. I don't know why because I clearly set the tag and also mark it as a delegate. thank you.
Adding some clarity and more suggestions to the valid answer by #jawadAli, as I feel you are still new to iOS development.
You are trying to get the tableView from the textField. But you will not get it by referring to the superview of textField. Because the view hierarchy would be like this:
UITableView > UITableViewCell > contentView > Your text field.
There can also be some more views in the view hierarchy, so you need to keep traversing through the superview chain till you get the UITableView. And #jawadAli has posted the code on how to get it.
But overall that is an incorrect approach. You should use delegation. I.e. your cell should call a method when it has resigned as first responder. And your table view controller will receive that call.
Then your view controller has to get the next cell and make it the first responder.
And if this doesn't make any sense to you, then I would very strongly suggest that you learn about Delegation. It's ubiquitous in iOS' libraries.
EDIT:
Approach to use delegation.
Create a protocol, let's say CellDelegate that has a function like func didFinishDataCapture(forCell: UITableViewCell).
The cell will have a delegate property of type CellDelegate.
The controller will conform to CellDelegate and will set itself as the cell's delegate in func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath)
Now in your cell, when you are done with the text field (which you would know as cell would be the text field's delegate), you call your own delegate's function i.e. delegate.didFinishDataCapture(forCell: self).
In your implementation of didFinishDataCapture in the controller, you will know which cell has finished with the data capture and can put the logic on what to do next.
It should be nil as textField.superview is your cell class ... and your cell class does not have the view with required Tag .. so it will return nil..
import UIKit
extension UIView {
func lookForSuperviewOfType<T: UIView>(type: T.Type) -> T? {
guard let view = self.superview as? T else {
return self.superview?.lookForSuperviewOfType(type: type)
}
return view
}
}
Get tableView through this extension like this
let tableView = self.view.lookForSuperviewOfType(type: UITableView.self)
your function will become
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
let tableView = self.view.lookForSuperviewOfType(type: UITableView.self)
if let cell = tableView?.cellForRow(at: IndexPath(row: textField.tag+1, section: 0)) as? CustomCell {
cell.box.becomeFirstResponder()
} else {
textField.resignFirstResponder()
}
return true
}
I am trying to get into MVVM in Swift and I am wondering how to handle events in subviews in MVVM, and how these events can travel up the chain of views/viewmodels. I'm talking about pure Swift for now (no SwiftRx etc.).
Example
Say I have a TableViewController with a TableViewModel. The view model holds an array of objects and creates a TableCellViewModel for each one, since each cell represents one of these objects. The TableViewController gets the number of rows to display from its model and also the view model for each cell, so it can pass it along to the cell.
We then have a TableCell and each cell has a TableCellViewModel. The TableCell queries its model for things like user-facing strings etc.
Now let's say TableCell also has a delete button that delete's that row. I'm wondering how to handle that: Usually, the cell would forward the button press to its view model, but this is not where we need it - we eventually need to know about the button press in either TableViewController or TableViewModel, so we can remove the row from the table view.
So the question is:
How does the button event get from a TableCell upwards in the view chain in MVVM?
Code
As requested in the comments, code that goes with the example:
class TableViewController: UIViewController, UITableViewDataSource {
var viewModel: TableViewModel = TableViewModel()
// setup and such
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.viewModel.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! TableCell
cell.viewModel = self.viewModel.cellViewModel(at: indexPath.item)
return cell
}
}
class TableViewModel {
// setup, get data from somewhere, ...
var count: Int {
return self.modelObjects.count
}
func cellViewModel(at index: Int) -> TableCellViewModel {
let modelObject = self.modelObjects[index]
let cellViewModel = TableCellViewModel(modelObject: modelObject)
return cellViewModel
}
}
class TableCell {
var viewModel: TableCellViewModel!
// setup UI, do what a cell does
func viewModelChanged() {
self.titleLabel.text = self.viewModel.title()
}
func deleteButtonPressed(_ sender: UIButton) {
// Oh, what to do, what to do?
}
}
class TableCellViewModel {
private var modelObject: ModelObject
init(modelObject: ModelObject) {
self.modelObject = modelObject
}
func title() -> String {
return self.modelObject.title
}
}
TableViewModel is the source of truth, so all global operations should be performed in there. Pressing a button is completely UI operation and viewModel shouldn't handle this in direct way.
So, for now we know two facts:
TableViewModel should delete the cell from array and then viewController should handle the deletion animation process;
Button press shouldn't be handled in child viewModel.
According to this you can achieve it by:
Pass button pressed event up to viewController (use callback or delegate pattern);
Call TableViewModel method to delete specific cell:
viewModel.deleteCell(at: indexPath)
Properly handle deletion animation in viewController.
may be you can use nextResponder util nextResponder is VC, and VC responder to delegate (eg:CellEventDelegate) that handle delete data and cell
UIResponder *nextResponder = pressedCell.nextResponder;
while (nextResponder) {
if ([nextResponder conformsToProtocol:#protocol(CellEventDelegate)]) {
if ([nextResponder respondsToSelector:#selector(onCatchEvent:)]) {
[((id<CellEventDelegate>)nextResponder) onCatchEvent:event];
}
break;
}
nextResponder = nextResponder.nextResponder;
}
I have a text field in a tableView. I need to get the position of textfield but the problem is there are multiple section in it. I am able to get only one thing section or row using textfield.tag but I need both.
You can find the parent UIResponder of any class by walking up the UIResponder chain; both UITextField and UITableViewCell inherit from UIView, which inherits from UIResponder, so to get the parent tableViewCell of your textfield you can call this function on your textfield:
extension UIResponder {
func findParentTableViewCell () -> UITableViewCell? {
var parent: UIResponder = self
while let next = parent.next {
if let tableViewCell = parent as? UITableViewCell {
return tableViewCell
}
parent = next
}
return nil
}
}
Then once you have the tableViewCell, you just ask the tableView for its index path with tableView.indexPAth(for:)
You never need to use the tag field:
guard let cell = textField.findParentTableViewCell (),
let indexPath = tableView.indexPath(for: cell) else {
print("This textfield is not in the tableview!")
}
print("The indexPath is \(indexPath)")
You can use a variation of a previous answer that I wrote.
Use a delegate protocol between the cell and the tableview. This allows you to keep the text field delegate in the cell subclass, which enables you to assign the touch text field delegate to the prototype cell in Interface Builder, while still keeping the business logic in the view controller.
It also avoids the potentially fragile approach of navigating the view hierarchy or the use of the tag property, which has issues when cells indexes change (as a result of insertion, deletion or reordering), and which doesn't work where you need to know a section number as well as a row number, as is the case here.
CellSubclass.swift
protocol CellSubclassDelegate: class {
func textFieldUpdatedInCell(_ cell: CellSubclass)
}
class CellSubclass: UITableViewCell {
#IBOutlet var someTextField: UITextField!
var delegate: CellSubclassDelegate?
override func prepareForReuse() {
super.prepareForReuse()
self.delegate = nil
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool
self.delegate?.textFieldUpdatedInCell(self)
return yes
}
ViewController.swift
class MyViewController: UIViewController, CellSubclassDelegate {
#IBOutlet var tableview: UITableView!
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! CellSubclass
cell.delegate = self
// Other cell setup
}
// MARK: CellSubclassDelegate
func textFieldUpdatedInCell(_ cell: CellSubclass) {
guard let indexPath = self.tableView.indexPathForCell(cell) else {
// Note, this shouldn't happen - how did the user tap on a button that wasn't on screen?
return
}
// Do whatever you need to do with the indexPath
print("Text field updated on row \(indexPath.row) of section \(indexPath.section")
}
}
You can also see Jacob King's answer using a closure rather than a delegate pattern in the same question.
My table view allows multiple cell selection, where each cell sets itself as selected when a button inside the cell has been clicked (similar to what the gmail app does, see picture below). I am looking for a way to let the UITableViewController know that cells have been selected or deselected, in order to manually change the UINavigationItem. I was hoping there is a way to do this by using the delegate methods, but I cannot seem to find one. didSelectRowAtIndexPath is handling clicks on the cell itself, and should not affect the cell's selected state.
The most straight forward way to do this would be to create our own delegate protocol for your cell, that your UITableViewController would adopt. When you dequeue your cell, you would also set a delegate property on the cell to the UITableViewController instance. Then the cell can invoke the methods in your protocol to inform the UITableViewController of actions that are occurring and it can update other state as necessary. Here's some example code to give the idea (note that I did not run this by the compiler, so there may be typos):
protocol ArticleCellDelegate {
func articleCellDidBecomeSelected(articleCell: ArticleCell)
func articleCellDidBecomeUnselected(articleCell: ArticleCell)
}
class ArticleCell: UICollectionViewCell {
#IBAction private func select(sender: AnyObject) {
articleSelected = !articleSelected
// Other work
if articleSelected {
delegate?.articleCellDidBecomeSelected(self)
}
else {
delegate?.articleCellDidBecomeUnselected(self)
}
}
var articleSelected = false
weak var delegate: ArticleCellDelegate?
}
class ArticleTableViewController: UITableViewController, ArticleCellDelegate {
func articleCellDidBecomeSelected(articleCell: ArticleCell) {
// Update state as appropriate
}
func articleCellDidBecomeUnselected(articleCell: ArticleCell) {
// Update state as appropriate
}
// Other methods ...
override tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueCellWithIdentifier("ArticleCell", forIndexPath: indexPath) as! ArticleCell
cell.delegate = self
// Other configuration
return cell
}
}
I would have a function like 'cellButtomDidSelect' in the view controller and in 'cellForRowAtIndexPath', set target-action to the above mentioned function
I have a UICollectionView containing a matrix of text fields. Since the number of text fields per row can be high, I implemented my custom UICollectionViewLayout to allow scrolling in this screen. When the user submits the form, I want to validate the value entered in every text field, thus I need to loop all the cells.
The problem that I'm facing is that I was using collectionView.cellForItemAtIndexPath for this but then found out that it fails with invisible cells, as I saw on this this question.
I understand the approach in the answer to store the values of the data source (in arrays) and then to loop the data source instead, however I don't know how to do this. I tried using function editingDidEnd as an #IBAction associated to the text field but I don't know how to get the "coordinates" of that text field. My idea behind this is to store the value just entered by the user in a two-dimensions array that I'll use later on to loop and validate.
Many thanks for your help in advance!
You don't have to loop invisible cells. Keep using datasource approach. What you are looking for is the way to map textFields to the datasource.
There are many solutions, but the easy one is using Dictionary.
Here's the code for UITableViewDataSource but you can apply it to UICollectionViewDataSource
class MyCustomCell: UITableViewCell{
#IBOutlet weak var textField: UITextField!
}
class ViewController: UIViewController{
// datasource
var textSections = [ [ "one" , "two" , "three"] , [ "1" , "2" , "3"] ]
// textField to datasource mapping
var textFieldMap: [UITextField:NSIndexPath] = [:]
// MARK: - Action
func textChanged(sender: UITextField){
guard let indexPath = textFieldMap[sender] else { return }
guard let textFieldText = sender.text else { return }
textSections[indexPath.section][indexPath.row] = textFieldText
}
#IBAction func submitButtonTapped(){
// validate texts here
for textRow in textSections{
for text in textRow{
if text.characters.count <= 0{
return print("length must be > 0.")
}
}
}
performSegueWithIdentifier("goToNextPage", sender: self)
}
}
extension ViewController: UITableViewDataSource{
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("identifer") as! MyCustomCell
// set value corresponds to your datasource
cell.textField.text = textSections[indexPath.section][indexPath.row]
// set mapping
textFieldMap[cell.textField] = indexPath
// add action-target to textfield
cell.textField.addTarget(self, action: "textChanged:", forControlEvents: .EditingChanged)
return cell
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return textSections[section].count
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return textSections.count
}
}