Problem I want to allow users to hit 'swap' in a table cell and then find a different Realm object to populate the 2 text labels (for exercise name and number of reps) in the cell with the values from the new object.
Research There's quite a bit (admittedly old) on 'moving rows' (e.g. here How to swap two custom cells with one another in tableview?) and also here (UITableView swap cells) and then there's obviously a lot on reloading data in itself but I can't find anything on this use case.
What have I tried my code below works fine for retrieving a new object. i.e. there's some data in the cell, then when you hit the 'swapButton' it goes grabs another one ready to put in the tableView. I know how to reload data generally but not within one particular cell in situ (the cell that the particular swap button belongs to... each cell has a 'swap button').
I'm guessing I need to somehow find the indexRow of the 'swapButton' and then access the cell properties of that particular cell but not sure where to start (I've played around with quite a few different variants but I'm just guessing so it's not working!)
class WorkoutCell : UITableViewCell {
#IBOutlet weak var exerciseName: UILabel!
#IBOutlet weak var repsNumber: UILabel!
#IBAction func swapButtonPressed(_ sender: Any) {
swapExercise()
}
func swapExercise() {
let realmExercisePool = realm.objects(ExerciseGeneratorObject.self)
func generateExercise() -> WorkoutExercise {
let index = Int(arc4random_uniform(UInt32(realmExercisePool.count)))
return realmExercisePool[index].generateExercise()
}
}
//do something here like cell.workoutName
//= swapExercise[indexRow].generateExercise().name???
}
Hold your objects somewhere in a VC that shows UITableView. Then add the VC as the target to swap button. Implement swapping objects on button press and reload data of table view after.
The whole idea is to move logic to view controller, not in separate cell.
There are 2 ways.
1. Adding VS as button action target.
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = ... // get cell and configure it
cell.swapBtn.addTarget(self, action: #selector(swapTapped(_:)), for: .touchUpInside)
return cell
}
func swapTapped(_ button: UIButton) {
let buttonPosition = button.convertPoint(CGPointZero, toView: self.tableView)
let indexPath = self.tableView.indexPathForRowAtPoint(buttonPosition)!
// find object at that index path
// swap it with another
self.tableView.reloadData()
}
Make VC to be delegate of cell. More code. Here you create protocol in cell and add delegate variable. Then when you create cell you assign to VC as delegate for cell:
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = ... // get cell and configure it
cell.delegate = self
return cell
}
func swapTappedForCell(_ cell: SwapCell) {
// the same logic for swapping
}
Solution from OP I adapted the code here How to access the content of a custom cell in swift using button tag?
Using delegates and protocols is the most sustainable way to achieve this I think.
I hope this helps others with the same problem!
Related
again me with a short question since Swift is confusing me ATM - but I hope I will get used to it soon ;)
Ok so what I was wondering is: When I call a TableView and generate different Cells is there a way to Interrupt after a few and wait for User Input and react to it?
For Example: 2nd Cell is something like "Go to North or West" after that I want a User Input - with Buttons - in whatever direction he likes to go and react to it with following Cells (different Story Parts -> out of other Arrays?).
What is confusing me is that I just load the whole Application in viewDidLoad and i don't know how I can control the "Flow" within this.
I would really appreciate if someone could show me how I can achieve this maybe even with a small description about how I can control the Program Flow within the Method. I really think this knowledge and understanding would lift my understanding for Swift a few Levels higher.
Thanks in advance!
Here is my current Code which is not including any functionality for the named Question since I don't know how to manage this :)
import UIKit
class ViewController: UIViewController {
var storyLines = ["Test Cell 1 and so on first cell of many","second cell Go to North or West","third Cell - Buttons?"]
var actualTables = 1
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
tableView.dataSource = self
}
#IBOutlet weak var tableView: UITableView!
}
extension ViewController : UITableViewDataSource{
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return storyLines.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "TxtLine", for: indexPath)
cell.textLabel?.text = storyLines[indexPath.row]
cell.textLabel?.numberOfLines = 0;
cell.textLabel?.lineBreakMode = .byWordWrapping
return cell
}
}
Cocoa is event driven. You are always just waiting for user input. It's a matter of implementing the methods that Cocoa has configured to tell you about it.
So here, for example, if you want to hear about when the user presses a button, you configure the button with an action-and-target to call a method in your view controller when the user presses it. That way, your method can see which button the user pressed and remake the table view's data model (your storyLines array) and reload the table with the new data.
I have a table view with custom cells. They are quite tall, so only one cell is completely visible on the screen and maybe, depending on the position of that cell, the top 25% of the second one. These cells represent dummy items, which have names. Inside of each cell there is a button. When tapped for the first time, it shows a small UIView inside the cell and adds the item to an array, and being tapped for the second time, hides it and removes the item. The part of adding and removing items works fine, however, there is a problem related to showing and hiding views because of the fact that cells are reused in a UITableView
When I add the view, for example, on the first cell, on the third or fourth cell (after the cell is reused) I can still see that view.
To prevent this I've tried to loop the array of items and check their names against each cell's name label's text. I know that this method is not very efficient (what if there are thousands of them?), but I've tried it anyway.
Here is the simple code for it (checkedItems is the array of items, for which the view should be visible):
if let cell = cell as? ItemTableViewCell {
if cell.itemNameLabel.text != nil {
for item in checkedItems {
if cell.itemNameLabel.text == item.name {
cell.checkedView.isHidden = false
} else {
cell.checkedView.isHidden = true
}
}
}
This code works fine at a first glance, but after digging a bit deeper some issues show up. When I tap on the first cell to show the view, and then I tap on the second one to show the view on it, too, it works fine. However, when I tap, for example, on the first one and the third one, the view on the first cell disappears, but the item is still in the array. I suspect, that the reason is still the fact of cells being reused because, again, cells are quite big in their height so the first cell is not visible when the third one is. I've tried to use the code above inside tableView(_:,cellForRow:) and tableView(_:,willDisplay:,forRowAt:) methods but the result is the same.
So, here is the problem: I need to find an EFFICIENT way to check cells and show the view ONLY inside of those which items are in the checkedItems array.
EDITED
Here is how the cell looks with and without the view (the purple circle is the button, and the view is the orange one)
And here is the code for the button:
protocol ItemTableViewCellDelegate: class {
func cellCheckButtonDidTapped(cell: ExampleTableViewCell)
}
Inside the cell:
#IBAction func checkButtonTapped(_ sender: UIButton) {
delegate?.cellCheckButtonDidTapped(cell: self)
}
Inside the view controller (NOTE: the code here just shows and hides the view. The purpose of the code is to show how the button interacts with the table view):
extension ItemCellsTableViewController: ItemTableViewCellDelegate {
func cellCheckButtonDidTapped(cell: ItemTableViewCell) {
UIView.transition(with: cell.checkedView, duration: 0.1, options: .transitionCrossDissolve, animations: {
cell.checkedView.isHidden = !cell.checkedView.isHidden
}, completion: nil)
}
EDITED 2
Here is the full code of tableView(_ cellForRowAt:) method (I've deleted the looping part from the question to make it clear what was the method initially doing). The item property on the cell just sets the name of the item (itemNameLabel's text).
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if let cell = tableView.dequeueReusableCell(withIdentifier:
ItemTableViewCell.identifier, for: indexPath) as? ItemTableViewCell{
cell.item = items[indexPath.row]
cell.delegate = self
cell.selectionStyle = .none
return cell
}
return UITableViewCell()
}
I've tried the solution, suggested here, but this doesn't work for me.
If you have faced with such a problem and know how to solve it, I would appreciate your help and suggestions very much.
Try this.
Define Globally : var arrIndexPaths = NSMutableArray()
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 30
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell:TableViewCell = self.tblVW.dequeueReusableCell(withIdentifier: "TableViewCell", for: indexPath) as! TableViewCell
cell.textLabel?.text = String.init(format: "Row %d", indexPath.row)
cell.btn.tag = indexPath.row
cell.btn.addTarget(self, action: #selector(btnTapped), for: .touchUpInside)
if arrIndexPaths.contains(indexPath) {
cell.backgroundColor = UIColor.red.withAlphaComponent(0.2)
}
else {
cell.backgroundColor = UIColor.white
}
return cell;
}
#IBAction func btnTapped(_ sender: UIButton) {
let selectedIndexPath = NSIndexPath.init(row: sender.tag, section: 0)
// IF YOU WANT TO SHOW SINGLE SELECTED VIEW AT A TIME THAN TRY THIS
arrIndexPaths.removeAllObjects()
arrIndexPaths.add(selectedIndexPath)
self.tblVW.reloadData()
}
I would keep the state of your individual cells as part of the modeldata that lies behind every cell.
I assume that you have an array of model objects that you use when populating you tableview in tableView(_:,cellForRow:). That model is populated from some backend service that gives you some JSON, which you then map to model objects once the view is loaded the first time.
If you add a property to your model objects indicating whether the cell has been pressed or not, you can use that when you populate your cell.
You should probably create a "wrapper object" containing your original JSON data and then a variable containing the state, lets call it isHidden. You can either use a Bool value or you can use an enum if you're up for it. Here is an example using just a Bool
struct MyWrappedModel {
var yourJSONDataHere: YourModelType
var isHidden = true
init(yourJSONModel: YourModelType) {
self.yourJSONDataHere = yourJSONModel
}
}
In any case, when your cell is tapped (in didSelectRow) you would:
find the right MyWrappedModel object in your array of wrapped modeldata objects based on the indexpath
toggle the isHidden value on that
reload your affected row in the table view with reloadRows(at:with:)
In tableView(_:,cellForRow:) you can now check if isHidden and do some rendering based on that:
...//fetch the modelObject for the current IndexPath
cell.checkedView.isHidden = modelObject.isHidden
Futhermore, know that the method prepareForReuse exists on a UITableViewCell. This method is called when ever a cell is just about to be recycled. That means that you can use that as a last resort to "initialize" your table view cells before they are rendered. So in your case you could hide the checkedView as a default.
If you do this, you no longer have to use an array to keep track of which cells have been tapped. The modeldata it self knows what state it holds and is completely independent of cell positions and recycling.
Hope this helps.
I have a button in a cell as a toggle to check in members in a club. When I check in a member, I need the button's state to stay ON after scrolling, but it turns back off. Here is the cellForRow method:
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = self.membersTableVw.dequeueReusableCell(withIdentifier: "CellMembersForCoach", for: indexPath) as! CellMembersForCoach
let member = members[indexPath.row]
cell.setMember(member)
cell.cellController = self
return cell
}
Here is the portion in the custom cell class where I toggle the button
#IBOutlet weak var checkBtn: UIButton!
#IBAction func setAttendance(_ sender: Any){
// toggle state
checkBtn.isSelected = !checkBtn.isSelected
}
The toggling works but after scrolling the table, the button state changes back to original. Any suggestion is appreciated.
This happens because you are reusing the cells.
You need to keep track of which cells have been selected. Perhaps in your member's class. Then when you are in your cellForRowAt you should check if this cell has been selected before and set the correct state for your button.
This is because of tableview is reusing your cell. so you have to maintain button as per tableView data source.
Shamas highlighted a correct way to do it, so I'll share my whole solution.
I created a singleton class to store an array of checked cells:
class Utility {
// Singleton
private static let _instance = Utility()
static var Instance: Utility{
return _instance
}
var checkedCells = [Int]()
In the custom cell class I have action method wired to the check button to add and remove checked cells:
#IBOutlet weak var checkBtn: UIButton!
#IBAction func setAttendance(_ sender: Any){
// Get cell index
let indexPath :NSIndexPath = (self.superview! as! UITableView).indexPath(for: self)! as NSIndexPath
if !checkBtn.isSelected{
Utility.Instance.checkedCells.append(indexPath.row)
}else{
// remove unchecked cell from list
if let index = Utility.Instance.checkedCells.index(of: indexPath.row){
Utility.Instance.checkedCells.remove(at: index)
}
}
// toggle state
checkBtn.isSelected = !checkBtn.isSelected
}
In the cellForRowAt method in the view controller I check if the cell row is in the array and decide if the toggle button should be checked:
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = self.membersTableVw.dequeueReusableCell(withIdentifier: "CellMembersForCoach", for: indexPath) as! CellMembersForCoach
if Utility.Instance.checkedCells.contains(indexPath.row){
cell.checkBtn.isSelected = true
}
return cell
}
The problem is here:
checkBtn.isSelected = !checkBtn.isSelected
This code will reflect the button selection state every time the cell is configured when the delegate cellForRowAt invokes. So if you selected it before, now it turns to not-selected.
Since the tableView is reusing cells you code is not going to work.
You have to keep track of each button when selected and set it again when tableview is reusing cells when you scroll.
Solution : You can take an array(contains bool) which is size of your tableview data.
So you have to set state of button using array and update array when selected or deselected.
I have one view controller named TableViewController and another customised cell called feed.swift
The cells are getting reused properly and I have put tags on various buttons as I wan't to know what button of what feed is pressed on.
In my cellForRowAtIndexPath I'm populating my username with json that I have parsed. It looks like this
cell.username.text = username[indexPath.row]
output-> ["andre gomes", "renato sanchez", "renato sanchez"]
Then I have tagged my username button like this
cell.usernamePress.tag = indexPath.row
This is going on in my TableViewController
In my feed.swift I'm checking if a button is pressed and printing out the tag assigned to that button
#IBAction func usernameBut(sender: AnyObject) {
print(usernamePress.tag)
}
output-> 2
Now I need to access the username array of TableViewController in feed.swift and do something like username[usernamePress.tag]
I tried making a global.swift file but I'm not able to configure it for an array of strings.
import Foundation
class Main {
var name:String
init(name:String) {
self.name = name
}
}
var mainInstance = Main(name: "hello")
Even after doing this I tried printing mainInstance.name and it returned hello even after changing it. I want a solution where the array of strings holds the values I set in TableViewController and I can be able to use them in feed.swift
Any suggestions would be welcome! I'm sorry if there are any similar question regarding this but I'm not able to figure out how to use it for a mutable array of strings
I suggest you don't use the array directly in your FeedCell but instead return the press-event back to your TableViewController where you handle the event. According to the MVC Scheme, which is the one Apple requests you to use (checkout Apples documentation), all your data-manipulation should happen in the Controller, which then prepares the Views using this data. It is not the View that is in charge to display the right values.
To solve your problem I would choose to pass back the press-event via the delegation-pattern, e.g. you create a FeedCellDelegate protocol that defines a function to be called when the button is pressed:
protocol FeedCellDelegate {
func feedCell(didPressButton button: UIButton, inCell cell: FeedCell)
}
Inside your FeedCell you then add a delegate property, which is informed about the event by the View:
class FeedCell {
var delegate: FeedCellDelegate?
...
#IBAction func pressedUsernameButton(sender: UIButton) {
delegate?.feedCell(didPressButton: sender, inCell: self)
}
}
If your TableViewController then conforms to the just defined protocol (implements the method defined in there) and you assign the ViewController as the View's delegate, you can handle the logic in the Controller:
class TableViewController: UITableViewController, FeedCellDelegate {
...
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("FeedCell", forIndexPath: indexPath) as! FeedCell
cell.delegate = self
// Further setup
return cell
}
func feedCell(didPressButton button: UIButton, inCell cell: FeedCell) {
guard let indexPath = tableView.indexPathForCell(cell) else { return }
// Do your event-handling
switch (button.tag) {
case 2: print("Is username button")
default: print("Press not handled")
}
}
}
As you might recognize I changed your class name. A Feed sounds more like a Model-class whereas FeedCell implies its role to display data. It makes a programmer's life way easier if you choose self-explaining names for your classes and variables, so feel free to adapt that. :)
you should add a weak array property to the tableViewCell:
weak var userNameArray:[String]?
Then in your tableViewController pass the username array into the cell:
fun tableView(tableView:UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
// create the cell, then...
if let array = self.username {
cell.userNameArray = array
}
}
Then you can use the array in the cell itself to populate its fields handle button taps, etc.
I have a basic method for populating a tableView with a custom cell in Swift
func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! {
let object = array[UInt(indexPath!.row)] as Word
var cell:DictionaryTableViewCell = self.tableView.dequeueReusableCellWithIdentifier("dictionaryCell") as DictionaryTableViewCell
cell.originalText.text = object.original
return cell
}
Works fine. Now, I got a custom cell DictionaryTableViewCell with custom properties and some IBActions (for different buttons inside that cell).
My question is: How do I expose data that was passed to the cell from tableView and use it from inside my custom cell controller? For instance I would like to be able to manipulate it for each cell using IBActions.
For now my custom cell controller is nothing fancy
class DictionaryTableViewCell: UITableViewCell {
#IBOutlet weak var originalText: UILabel!
#IBAction func peak(sender: AnyObject) {
}
}
Is there a custom property I can use to recover data passed onto it? Or do I have to implement some sort of a protocol? If so - how?