I have a UITableView and I want to delete the sections and rows. I am trying to delete the whole section with its rows inside it. Following are the cases which is confusing for me.
When I try to delete section from top to bottom or from bottom to top in order all sections gets deleted without error
When I try to delete sections in random i.e first I delete top first section and then when I try to delete 4th or 8th or last section the app crashes its own
Crash Log
Fatal error: Index out of range
here is how I am doing it:
func onHeaderSwippedRight(ClickedSection: IndexPath) {
dataSource.remove(at: ClickedSection.section)
// use the UITableView to animate the removal of this row
tableView.beginUpdates()
tableView.deleteSections(IndexSet.init(integer : ClickedSection.section), with: .automatic)
tableView.endUpdates()
}
The Index path that I am passing into this function onHeaderSwippedRight(ClickedSection: IndexPath) is passwed by delegated method. Bcz In my Class I am passing it while setting up my data of section
A raw guess of mine is that after removing the section tableview must update the indices of the section, because as I am removing data from data source it must not get Index out of bound issue if sections gets update themselves
please help and tell me what I am doing wrong
Update;
public class ListModel : Object {
var Id : String = ""
var UserId : Int64 = 0
var Name : String? = ""
var Items : [ListDetailServiceModel]? = []}
This is my model, and I am having list of this like so
let dataSource :[ListModel] = []
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.
I'm new to IOS so forgive me for my coding mistakes. I'm facing an issue where I have a tableView Controller with two sections. The first section has a button, when clicked, appends data into an array and deletes it's own row in the first section (i did this as there are extra non related rows in the first section). The number of rows in the second section is based upon array.count.
My issue is that I tried begin/end update, and it still doesn't work. Whenever I run the code below and run the startNewDay function (when the button is clicked), this error occurs:
'attempt to insert row 0 into section 1, but there are only 0 rows in section 1 after the update'
This doesn't make any sense, as I appended the array already before I inserted the new rows. The array was empty before I appended it. Shouldn't there be the same number of rows in the second section as array.count?
Table View Delegate code:
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 2
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if section == 0 {
if dataModel.lists[0].dayHasStarted == false {
return 2
} else {
return 1
}
} else {
if itemDoneCount == dataModel.lists[0].item.count && dataModel.lists[0].doneButtonVisible {
return dataModel.lists[0].item.count + 1
} else {
return dataModel.lists[0].item.count
}
}
}
startNewDay button function when pressed:
#IBAction func startNewDayDidPress(sender: AnyObject) {
dataModel.lists[0].dayHasStarted = true
dataModel.lists[0].startDate = NSDate()
addItemButton.enabled = !addItemButton.enabled
// deleting start new day button
let indexPath = NSIndexPath(forRow: 1, inSection: 0)
let indexPaths = [indexPath]
tableView.beginUpdates()
tableView.deleteRowsAtIndexPaths(indexPaths, withRowAnimation: .Fade)
tableView.endUpdates()
// Inserting new array elements and rows into 2nd section
let ritualsArray = dataModel.lists[0].rituals
var itemsArray = dataModel.lists[0].item
itemsArray.appendContentsOf(ritualsArray)
tableView.beginUpdates()
var insertRitualsArray = [NSIndexPath]()
for item in itemsArray {
let itemIndex = itemsArray.indexOf(item)
let indexPath = NSIndexPath(forRow: itemIndex!, inSection: 1)
insertRitualsArray.append(indexPath)
}
tableView.insertRowsAtIndexPaths(insertRitualsArray, withRowAnimation: .Top)
tableView.endUpdates()
}
SOLVED
The problem of this code is not at all related to the previous title of this thread, which may be misleading to people having the same issue as mine. Hence, I will be changing it. The previous title (for the curious) was :
"tableView.begin/end update not updating number of rows in section"
Just for others who might come across this issue, the issue isn't in the tableView delegate, nor is it in reloading the tableview data. For readability, I placed both dataModel.list[0].item into itemsArray and dataModel.list[0].item into ritualsArray. This apparently updates the itemsArray when appended but not the initial dataModel.list[0].item instead, which caused the second section in the tableView not to load the new number of rows, causing the error when inserting rows into non-existant rows.
Hence instead of:
let ritualsArray = dataModel.lists[0].rituals
var itemsArray = dataModel.lists[0].item
itemsArray.appendContentsOf(ritualsArray)
this solved it:
dataModel.list[0].item += dataModel.list[0].rituals
Hope it helps any beginner like me out there that comes across this issue.
Latest update
I found out recently that an array is of value type, and not reference type. Hence placing an array into a variable makes a copy of that array instead of serving as a placeholder for the original array.
Beginner mistake opps.
The error you are receiving means that the datasource contains a different number of items to however many there would be after inserting or deleting rows. This probably means that the data are not being inserted into your datasource array, or that the data do not match the criteria in the if statements in your numberOfRowsInSection function. To troubleshoot this, you should log the contents of the datasource array after modifying it to check what its contents are. If they are what you are expecting (I.e. The data have been added correctly) then the issue is in the way you are evaluating its contents to establish the number of rows. If the contents are not what you are expecting, then the issue is in the way you are inserting the data into the datasource array.
I had a similar problem after deleting a row. It seems that if
numberOfRowsInSection is not coherent (equal to last value -1) this error appears.
I see that there's a condition in your numberOfRowsInSection, this is perhaps the culprit
I have two tables in which I am dragging and dropping between them: sourceTableView and targetTableView. They each have their own tableViewController. A parentContainerViewController manages a 'slide out' UI which allows the user to 'longPressGesture' on the sourceTableView cell which causes sourceTableView to slide out exposing the targetTableView below at which time the user can 'drop' the dragged cell into place within the targetTableView. All works well as it should until the targetTableView grows to about 21-27 rows in size. Once we get to this size and if I re-run the project I start to get the NSInternalInconsistencyException. The detail of the error reads: reason: 'Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (27) must be equal to the number of rows contained in that section before the update (0), plus or minus the number of rows inserted or deleted from that section (1 inserted, 0 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).'
At first I thought I was getting a race condition issue since the number of rows before the update is "0" and after it is "27". Maybe the tableView wasn't able to load before the user drags in the item and calls the insertIndex method on tableView. But then I noticed that it works fine until we get to a certain length. Race condition wouldn't make sense in this case. Now I am thinking it has something to do with with 'visible cell' loaded vs not loaded. But why would it be '0' rows? I have looked all over for the answer. There are many NSInconsistency but none that seem to answer my specific problem.
This is the function call to tell targetTableViewController to insert an item into its datasource then tells targetTableView to insertRowsAtIndexPath :
dragDropDataSource.tableView(self, insertDataItem: item, atIndexPath: indexPath)
self.beginUpdates()
self.insertRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Fade)
self.endUpdates()
Here is the targetTableViewController code implementing the above call:
func tableView(tableView: UITableView, insertDataItem dataItem : AnyObject, atIndexPath indexPath: NSIndexPath) -> Void {
if let di = dataItem as? DataItem {
data.insert(di, atIndex: indexPath.row)
}
data is the array that stores the 'DataItems' which are shown in the tableView rows.
Additionally. The targetTableView is initialized with data via a call in its viewDidLoad() to getMyTopTen()
func getMyTopTen() {
let pwAPI = PowWowAPI()
pwAPI.getMyTopTen(self.boardId!) {
(entries:[Entry])in
for(var i=0; i < entries.count; i++) {
let dataItem = DataItem(indexes: String(i), entry: entries[i])
self.data.append(dataItem)
}
}
dispatch_async(dispatch_get_main_queue()) {
self.targetTableView.reloadData()
}
}
I hope I have explained the problem sufficiently. If not please help me make this question better. I am new to asking questions here.
This question already has answers here:
How to detect the end of loading of UITableView
(22 answers)
Closed 6 years ago.
I need to call a function after the UITableView has been loaded completely. I know that in most cases not every row is displayed when you load the view for the first time, but in my case, it does as I only have 8 rows in total.
The annoying part is that the called function needs to access some of the tableView data, therefore, I cannot call it before the table has been loaded completely otherwise I'll get a bunch of errors.
Calling my function in the viewDidAppear hurts the user Experience as this function changes the UI. Putting it in the viewWillAppear screws up the execution (and I have no idea why) and putting it in the viewDidLayoutSubviews works really well but as it's getting called every time the layout changes I'm afraid of some bugs that could occur while it reloads the tableView.
I've found very little help about this topic. Tried few things I found here but it didn't work unfortunately as it seems a little bit outdated. The possible duplicate post's solution doesn't work and I tried it before posting here.
Any help is appreciated! Thanks.
Edit: I'm populating my tableView with some data and I have no problems with that. I got 2 sections and in each 4 rows. By default the user only sees 5 rows (4 in the first section, and only one in the second the rest is hidden). When the user clicks on the first row of the first section it displays the first row of the second section. When he clicks on the second row of the first section it displays two rows of the second section, and so on. If the user then clicks on the first row of the first section again, only one cell in the second section is displayed. He can then save his choice.
At the same time, the system changes the color of the selected row in the first section so the users know what to do.
Part of my issue here is that I want to update the Model in my database. If the users want to modify the record then I need to associate the value stored in my database with the ViewController. So for example, if he picked up the option 2 back then, I need to make sure the second row in the first section has a different color, and that two rows in the second sections are displayed when he tries to access the view.
Here's some code :
func setNonSelectedCellColor(indexPath: NSIndexPath) {
let currentCell = tableView.cellForRowAtIndexPath(indexPath)
currentCell?.textLabel?.textColor = UIColor.tintColor()
for var nbr = 0; nbr <= 3; nbr++ {
let aCell = tableView.cellForRowAtIndexPath(NSIndexPath(forRow: nbr, inSection: 0))
let aCellIndexPath = tableView.indexPathForCell(aCell!)
if aCellIndexPath?.row != indexPath.row {
aCell?.textLabel?.textColor = UIColor.blackColor()
}
}
}
func hideAndDisplayPriseCell(numberToDisplay: Int, hideStartIndex: Int) {
for var x = 1; x < numberToDisplay; x++ {
let priseCell = tableView.cellForRowAtIndexPath(NSIndexPath(forRow: x, inSection: 1))
priseCell?.hidden = false
}
if hideStartIndex != 0 {
for var y = hideStartIndex; y <= 3; y++ {
let yCell = tableView.cellForRowAtIndexPath(NSIndexPath(forRow: y, inSection: 1))
yCell?.hidden = true
}
}
}
These two functions are getting called every time the user touches a row :
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
let path = (indexPath.section, indexPath.row)
switch path {
case(0,0):
setNonSelectedCellColor(indexPath)
hideAndDisplayPriseCell(1, hideStartIndex: 1)
data["frequencyType"] = Medecine.Frequency.OneTime.rawValue
case(0,1):
setNonSelectedCellColor(indexPath)
hideAndDisplayPriseCell(2, hideStartIndex: 2)
data["frequencyType"] = Medecine.Frequency.TwoTime.rawValue
case(0,2):
setNonSelectedCellColor(indexPath)
hideAndDisplayPriseCell(3, hideStartIndex: 3)
data["frequencyType"] = Medecine.Frequency.ThreeTime.rawValue
case(0,3):
setNonSelectedCellColor(indexPath)
hideAndDisplayPriseCell(4, hideStartIndex: 0)
data["frequencyType"] = Medecine.Frequency.FourTime.rawValue
default:break
}
}
I store the values in a dictionary so I can tackle validation when he saves.
I'd like the first two functions to be called right after my tableView has finished loading. For example, I can't ask the data source to show/hide 1 or more rows when I initialize the first row because those are not created yet.
As I said this works almost as intended if those functions are called in the viewDidAppear because it doesn't select the row immediately nor does it show the appropriate number of rows in the second sections as soon as possible. I have to wait for 1-2s before it does.
If you have the data already that is used to populate the tableView then can't you use that data itself in the function? I am presuming that the data is in the form of an array of objects which you are displaying in the table view. So you already have access to that data and could use it in the function.
But if that's not the case then and if your table view has only 8 rows then you can try implementing this function and inside that check the indexPath.row == 7 (8th row which is the last one).
tableView(tableView: UITableView, didEndDisplayingCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath)
Since all your rows are visible in one screen itself without scrolling you could use this function to determine that all the cells have been loaded and then call your function.
I'm receiving an error indicating that I need to update the number of rows in my UITableView after I have deleted a row. I realise that It's because I've not updated the amount of rows in the UITableView, I'm just not sure how to make this change in the code I have below.
Any assistance is really appreciated.
!-- code
NSIndexPath[] rowsToReload = new NSIndexPath[] {
NSIndexPath.FromRowSection(1, 1)
};
dv.TableView.BeginUpdates ();
dv.TableView.DeleteRows(rowsToReload,UITableViewRowAnimation.Automatic);
dv.TableView.EndUpdates ();
!-- error
Name: NSInternalInconsistencyException Reason: Invalid update: invalid number of rows in section 1. The number of rows contained in an existing section after the update (3) must be equal to the number of rows contained in that section before the update (3)
Your code above is OK. However, you need to call it after you have removed the corresponding items from your data source.
For example, if you are filling your table view from a List<string> (myList) and you wanted to remove the first row:
myList.RemoveAt(0); // remove the item from the list first
NSIndexPath[] rowsToDelete = new NSIndexPath[] {
NSIndexPath.FromRowSection(0, 0)
};
dv.TableView.DeleteRows(rowsToDelete, UITableViewRowAnimation.Automatic);
No need to wrap the DeleteRows call in a Begin/EndUpdates, as you only have one delete action to perform. That is used when you have multiple different actions (eg. DeleteRows + InsertRows) so that the animations are performed smoothly.
#Dimitris thanks for answering my question. I ended up solving the problem by:
calling the reload method on my UITableView
NSIndexPath[] rowsToReload = new NSIndexPath[] {
NSIndexPath.FromRowSection(1, 1)
};
dv.TableView.ReloadRows (rowsToReload,UITableViewRowAnimation.None);
in my UITableViewCell GetCell method
I removed the label, field and button that were included on the first load of the table. Since this screen in my app will be seen only once, when the user loads it for the first time.