I want to pass table cell's textLabel data of UITableViewController to NSArray. Those cell have identifier name Cells and accessory type checkmark
Code that does exactly what you asked is here:
func getCellsData() -> [String] {
var dataArray: [String] = []
for section in 0 ..< self.tableView.numberOfSections() {
for row in 0 ..< self.tableView.numberOfRowsInSection(section) {
let indexPath = NSIndexPath(forRow: row, inSection: section)
let cell = self.tableView.cellForRowAtIndexPath(indexPath)!
if cell.reuseIdentifier == "Cells" && cell.accessoryType == UITableViewCellAccessoryType.Checkmark {
dataArray.append(cell.textLabel!.text!)
}
}
}
return dataArray
}
But I would like to recommend you find different approach, because this is the rude traverse of tableView. You probably have your dataSource model that can give you ll data you need. Additionally, this code doesn't check for errors, for example if there is no text in cell at some indexPath
Two things I'd advise.
First, looks like you're using the checkmark accessory to indicate multiple selections. It's really intended for single selection, like a radio button. Better to use the allowMultipleSelectionsoption on the tableview. This will allow...
...the second thing. Copying text from cells into an array is the wrong way round to do it. Better to ask the table view and call it's - (NSArray *)indexPathsForSelectedRows this will give you an array of index paths to selected cells then you can ask for each cell and grab any data you want from it. This gives you better live data and prevents you unknowingly creating a circular reference from the view controller of the tableview and the content in the tableview cells.
Related
I have a tableview that the user edits information in using textfields, and I store that information into an array that keeps track of all the values. The issue occurs when the user scrolls back to a cell they already edited and the values the added previously are now values from other cells.
I understand that cells are reused, and as a result their data needs to be updated whenever they are being viewed again. I also learned that cellforrowat is called every time a cell is loaded into the view as opposed to just the first time a cell is created. I made a test project to figure out my problem.
My first attempt at solving the problem went like so
cellforrowat is called
if this is the first time the cell is being made set default values and add its data to the array keeping our cell data
If this is not the first time, draw information from the data source at indexpath.row and apply it to the cell
if cellInformation.count < (indexPath.row + 1) // Newly made cell
{
cell.value = 0
cell.tField.text = ""
cellInformation[cellInformation.count] = cell
}
else if (cellInformation.count >= indexPath.row) // Cell we've seen before
{
cell.configure(Value: cellInformation[indexPath.row]!.value) // Sets the textField.text to be the same as the cells value
}
This worked better but when I scrolled back to the top of my tableview, the top most cells were still getting random data. My next attempt generated an ID tag for each cell, and then checking if the id tag of the cell at cellforrowat matched any of the one's in the array.
if cellInformation.count < (indexPath.row + 1) // 0 < 1
{
cell.idTag = idTagCounter
idTagCounter += 1
cell.value = 0
cell.tField.text = ""
cellInformation[cellInformation.count] = cell
}
else if (cellInformation.count >= indexPath.row)
{
for i in 0...idTagCounter - 1
{
if(cell.idTag == cellInformation[i]?.idTag)
{
cell.configure(Value: cellInformation[i]!.value)
}
}
cell.configure(Value: cellInformation[indexPath.row]!.value)
}
This got pretty much the same results as before. When I debugged my program, I realized that when i scroll down my tableview for the first time, indexPath.row jumps from a value like 7 down to 2 and as I scroll more and more, the row goes further away from what it should be for that cell until it eventually stops at 0 even if there are more cells i can scroll to. Once the row hits 0, cellforrowat stops being called.
Any ideas on how i can accurately assign a cells values to the information in my array?
Your premise is wrong:
cellforrowat is called
if this is the first time the cell is being made set default values and add its data to the array keeping our cell data
If this is not the first time, draw information from the data source at indexpath.row and apply it to the cell
You should set up a model object that contains the data for the entries in your table view, and your cellForRowAt() method should fetch the entry for the requested IndexPath.
Your model can be as simple as an array of structs, with one struct for each entry in your table. If you use a sectioned table view you might want an array of arrays (with the outer array containing sections, and the inner arrays containing the entries for each section.)
You should not be building your model (array) in calls to cellForRowAt().
You also should not, not NOT be storing cells into your model. You should store the data that you display in your cells (text strings, images, etc. Whatever is appropriate for your table view.)
Assume that cellForRowAt() can request cells in any order, and ask for the same cells more than once.
Say we want to display an array of animals, and a numeric age:
struct Animal {
let species: String
let age: Int
}
//Create an array to hold our model data, and populate it with sample data
var animals: [Animal] = [
Animal(species: "Lion", age: 3),
Animal(species: "Tiger", age: 7),
Animal(species: "Bear", age: 4)
]
//...
func cellForRow(at indexPath: IndexPath) -> UITableViewCell? {
let cell = dequeueReusableCell(withIdentifier: "cell" for: indexPath)
let thisAnimal = animals[indexPath.row]
cell.textLabel.text = "\(thisAnimal.species). Age = \(thisAnimal.species)"
}
Note that for modern code (iOS >=14), you should really be using UIListContentConfigurations to configure and build your cells.
func convertPointToIndexPath(_ point: CGPoint) -> (UITableView, IndexPath)? {
if let tableView = [tableView1, tableView2, tableView3].filter({ $0.frame.contains(point) }).first {
let localPoint = scrollView.convert(point, to: tableView)
let lastRowIndex = focus?.0 === tableView ? tableView.numberOfRows(inSection: 0) - 1 : tableView.numberOfRows(inSection: 0)
let indexPath = tableView.indexPathForRow(at: localPoint) ?? IndexPath(row: lastRowIndex, section: 0)
return (tableView, indexPath)
}
return nil
}
So i got this method, which converts a CGPoint into the indexPath of the given uitableView. I struggle with the filter-Method on the array which contains uitableViews.
I got an array outside of this method which contains any number of uitableViews. For example:
public var littleKanbanColumnsAsTableViews: [UITableView] = []
So i got to make a change inside of the method. Like this:
if let tableView = littleKanbanColumnsAsTableViews.filter({ $0.frame.contains(point)}).first { ... }
Now when i click on any tableView on the gui, i track the coordinates of the point and transform it on the belonging tableview with the frame.contains(point) method.
My problem is that the filter is not working, it always gives me the first tableView back, no matter which tableview is clicked. Why it doesn't work with my littleKanbanColumnsAsTableViews-Array?
One hint:
let tableView = littleKanbanView.littleKanbanColumnsAsTableViews[3]
When i indexing its direct then it works. But i want it depending on which tableView is containing the clicked point.
Here is my array with the tableViews, in this case the array contains 5 tableviews.
array containing tableviews
Now i want to filter the tableView out of them, which includes the point from tapping on this tableView. How can i achieve this?
For more understanding, i add the ui, here is it:
UI of my app
When i click on this tableView it works, because it is the first element in my array of tableViews. So for this case the convertPointToIndexPath-Method is working.
But when i scroll horizontally to the second tableView for example and click on that, it doesn't work. Because I think the method gives me always the first element back, but i thought it filters it with the given condition.
What is the problem, why doesn't work the condition{ $0.frame.contains(point)}? It have to localize the tableView when the coordinates of the point are tracked.
Preferred Solution:
In this case the moment the first satisfying condition is met, the rest of the elements are not traversed.
if let tableView = littleKanbanColumnsAsTableViews.first(where: { $0.frame.contains(point) }) {
}
Not so efficient solution:
In this case all the elements in the array are traversed to build an array of table views that satisfy the condition. Then the first element of that filtered array is chosen.
if let tableView = (littleKanbanColumnsAsTableViews.filter{ $0.frame.contains(point)}).first {
}
I am trying to use a UITableview with multiple selection on and a check mark accessory view for selected rows. This is mostly working if I turn on and off the accessory view in tableView:didSelectRow.
However, I tried to build a selectAll method, and I found that the array of selected cells was being cleared after I had spun through all the cells and selected them if I then call reloadData().
I suspect reloading the table clears selection. I don't know of any other way to have all the cells drawn after I set the selected flag and accessory view.
I am wondering if I need to keep my own array of selected rows. Has anyone else built something like this? Its seems like a common scenario.
Any tips or sample code appreciated.
Take an Array and add the indexPath of each selected cell into it and put a condition in cellForRowAt... that if the Array contains that particular indexPath, set it as selected.
There are two approaches you can take. One is to track the selected row numbers. To do this, you can use an NSMutableIndexSet or its Swift counterpart IndexSet.
Essentially, when a row is selected, add it to the set. When you deselect it, remove it from the set. In cellForRowAtIndexPath you can use containsIndex to determine if a check mark should be shown or not.
Since you explicitly mention an issue with selection when you reload the table, it is worth considering the issue with storing row numbers (whether in a set or an array), and that is that row numbers can change.
Say I have selected rows 4,7 and 9 and these values are stored in the index set. When I reload the data, new data may have been inserted after the "old" row 8, so now I should be selecting rows 4,7 and 10, but I will be selecting 4,7 and 9 still.
A solution to this is to store some sort of unique identifier for the data that should be selected. This will depend on your data, but say you have a string that is unique for each item. You can store this string in a NSMutableSet or Swift Set, which again makes it easy to check if a given item is selected using contains
you need add some functionality in cellForRowAtIndexPath method like this ang your view controller code like this
let we take one example of photo gallery application
class CreateEvent: UIViewController,UITableViewDataSource,UITableViewDelegate {
var yourArray : [Photo] = [Photo]()
//MARK: - Content TableView Methods
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("CustomCell", forIndexPath: indexPath)
let objPhoto = yourArray[indexPath.row]
if objPhoto.isPhotoSelected == true
{
cell.accessoryType = .Checkmark
}
return cell
}
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath)
{
let objPhoto = yourArray[indexPath.row]
objPhoto.isPhotoSelected = true
let cell = tableView.cellForRowAtIndexPath(indexPath)
cell.accessoryType = .Checkmark
}
//MARK: Action Method
func selectAllPhoto()
{
for objPhoto in yourArray
{
objPhoto.isPhotoSelected = true
}
tableView.reloadData()
}
}
and one more thing you need to create your custom object like
class Photo: NSObject {
var photoName:String = ""
var isPhotoSelected = false
}
hope this will help you
The best approach for multiple selection is
Take a model object, in that take all your attributes and one extra boolean attribute (like isSelected) to hold the selection.
In case of selecting a row
Fetch the relevant object from the array
Then update the isSelected boolean (like isSelected = !isSelected) and reload table.
In case of select all case
Just loop through the array.
Fetch the model object from array.
make the isSelected = true.
After completion of loop, reload the table.
I have a UITableView with 5 custom UITableViewCells. In the custom UITableViewCells I have IBOutlets for my UI-elements (UILabel, UITextField). I cannot create IBOutlets for the UI-elements in my view controller because they are already linked to my custom UITableViewCells.
I want to be able to access the data in my UITableViewCells when the UIBarButtonItem of type "Save" is pressed. In order to parse the data from my UITableViewCells to my own class.
I have already written the unwind method in the return controller, and have written the prepareForSegue method in the source controller, got that working. I only need to retrieve the data from the custom UITableViewCells at that specific time (on save, not on finished editing textfield or when a table row has been dis-selected).
What would be the "best practice" to achieve this kind of behaviour?
Since I don't know what your custom cells look like, I'll just use a cell that has a single text field in it (named myTextField) as an example.
In the custom cell class, add a property like this:
var value: String? {
return myTextField.text
}
And in the save button's #IBAction method, do this:
var data = [String]()
let sections = numberOfSectionsInTableView(self.tableView)
for s in 0..<sections {
let rows = tableView(self.tableView, numberOfRowsInSection: s)
for r in 0..<rows {
let cell = tableView.cellForRowAtIndexPath(NSIndexPath(forRow: r, inSection: s)) as! YourCustomCell
data.append(cell.value)
}
}
And now you have an array of strings!
If your cell's data is not as simple as a string, please consider using Eureka.
Using Swift, how can I iterate over all the UITableCells given a section id (eg: all cells in section 2)?
I only see this method: tableView.cellForRowAtIndexPath, which returns 1 cell given the absolute index, so it doesn't help.
Is there an elegant and easy way?
Note: I want to set the AccesoryType to None for all of the cells in a section, programatically, say: after a button is clicked, or after something happends (what happends is not relevant for the question)
I have the reference for the UITableView and the index of the section.
You misunderstand how table views work. When you want to change the configuration of cells, you do not modify the cells directly. Instead, you change the data (model) for those cells, and then tell your table view to reload the changed cells.
This is fundamental, and if you are trying to do it another way, it won't work correctly.
You said "I need the array of cells before modifying them…" Same thing applies. You should not store state data in cells. As soon as a user makes a change to a cell you should collect the changes and save it to the model. Cells can scroll off-screen and their settings can be discarded at any time.
#LordZsolt was asking you to show your code because from the questions you're asking it's pretty clear you are going about things the wrong way.
EDIT:
If you are convinced that you need to iterate through the cells in a section then you can ask the table view for the number of rows in the target section, then you can loop from 0 to rows-1, asking the table view for each cell in turn using the UITableView cellForRowAtIndexPath method (which is different than the similarly-named data source method.) That method will give you cells that are currently visible on the screen. You can then make changes to those cells.
Note that this will only give you the cells that are currently on-screen. If there are other cells in your target section that are currently not visible those cells don't currently exist, and if the user scrolls, some of those cells might be created. For this reason you will need to save some sort of state information to your model so that when you set up cells from the target section in your datasource tableView:cellForRowAtIndexPath: method you can set them up correctly.
For Swift 4 I have been using something along the lines of the following and it seems to work pretty well.
for section in 0...self.tableView.numberOfSections - 1 {
for row in 0...self.tableView.numberOfRows(inSection: section) - 1 {
let cell = self.tableView.cellForRow(at: NSIndexPath(row: row, section: section) as IndexPath)
print("Section: \(section) Row: \(row)")
}
}
Im using same way of iterating all table view cells , but this code worked for only visible cells , so I'v just add one line allows iterating all table view cells wether visible they are or not
//get section of interest i.e: first section (0)
for (var row = 0; row < tableView.numberOfRowsInSection(0); row++)
{
var indexPath = NSIndexPath(forRow: row, inSection: 0)
println("row")
println(row)
//following line of code is for invisible cells
tableView.scrollToRowAtIndexPath(indexPath, atScrollPosition: UITableViewScrollPosition.Top, animated: false)
//get cell for current row as my custom cell i.e :roomCell
var cell :roomCell = tableView.cellForRowAtIndexPath(indexPath) as roomCell
}
* the idea is to scroll tableview to every row I'm receiving in the loop so, in every turn my current row is visible ->all table view rows are now visible :D
To answer my own question: "how can I iterate over all the UITableCells given a section id?":
To iterate over all the UITableCells of a section section one must use two methods:
tableView.numberOfRowsInSection(section)
tableView.cellForRowAtIndexPath(NSIndexPath(forRow: row, inSection: section))
So the iteration goes like this:
// Iterate over all the rows of a section
for (var row = 0; row < tableView.numberOfRowsInSection(section); row++) {
var cell:Cell = tableView.cellForRowAtIndexPath(NSIndexPath(forRow: row, inSection: section))?
// do something with the cell here.
}
At the end of my question, I also wrote a note: "Note: I want to set the AccesoryType to None for all of the cells in a section, programatically". Notice that this is a note, not the question.
I ended up doing that like this:
// Uncheck everything in section 'section'
for (var row = 0; row < tableView.numberOfRowsInSection(section); row++) {
tableView.cellForRowAtIndexPath(NSIndexPath(forRow: row, inSection: section))?.accessoryType = UITableViewCellAccessoryType.None
}
If there is a more elegant solution, go ahead and post it.
Note: My table uses static data.
Swift 4
More "swifty", than previous answers. I'm sure this can be done strictly with functional programming. If i had 5 more minutes id do it with .reduce instead. ✌️
func cells(tableView:UITableView) -> [UITableViewCell]{
var cells:[UITableViewCell] = []
(0..<tableView.numberOfSections).indices.forEach { sectionIndex in
(0..<tableView.numberOfRows(inSection: sectionIndex)).indices.forEach { rowIndex in
if let cell:UITableViewCell = tableView.cellForRow(at: IndexPath(row: rowIndex, section: sectionIndex)) {
cells.append(cell)
}
}
}
return cells
}
Im using this way of iterating all table view cells , but this code worked for only visible cells , so I'v just add one line allows iterating all table view cells wether visible they are or not
//get section of interest i.e: first section (0)
for (var row = 0; row < tableView.numberOfRowsInSection(0); row++)
{
var indexPath = NSIndexPath(forRow: row, inSection: 0)
println("row")
println(row)
//following line of code is for invisible cells
tableView.scrollToRowAtIndexPath(indexPath, atScrollPosition: UITableViewScrollPosition.Top, animated: false)
//get cell for current row as my custom cell i.e :roomCell
var cell :roomCell = tableView.cellForRowAtIndexPath(indexPath) as roomCell
}
* the idea is to scroll tableview to every row I'm receiving in the loop so, in every turn my current row is visible ->all table view rows are now visible
You can use
reloadSections(_:withRowAnimation:) method of UITableView.
This will reload all the cells in the specified sections by calling cellForRowAtIndexPath(_:). Inside that method, you can do whatever you want to those cells.
In your case, you can apply your logic for setting the appropriate accessory type:
if (self.shouldHideAccessoryViewForCellInSection(indexPath.section)) {
cell.accessoryType = UITableViewCellAccessoryTypeNone
}
I've wrote a simple extension based on Steve's answer. Returns the first cell of given type (if any) in a specified section.
extension UITableView {
func getFirstCell<T: UITableViewCell>(ofType type: T.Type, inSection section: Int = 0) -> T? {
for row in 0 ..< numberOfRows(inSection: section) {
if let cell = cellForRow(at: IndexPath(row: row, section: section)) as? T {
return cell
}
}
return nil
}
}