UITableView _contentOffsetForScrollingToRowAtIndexPath:atScrollPosition:]: section (3) beyond bounds (1).'
I've got an array of information being displayed at my tableview, and when I hit a button I'm wanting it to scroll down to a certain cell.
Initially I thought I was getting that error because of the way I was getting my index to jump to:
if let index = peopleListArray.index(where: { $0.UID == currentUser }) {
print(index)
let NSIndex = NSIndexPath(index: Int(index) )
tableView.reloadData()
print(peopleListArray.count)
print(NSIndex)
tableView.scrollToRow(at: NSIndex as IndexPath , at: .top, animated: true )
}
But then I replaced "let NSINDex... with
let NSIndex = NSIndexPath(index: 1 )
and it's still throwing the same error.
when I'm printing out my array count and my NSIndex I'm always getting an 8 for the count (which is correct) and I'm getting 3 for the NSINdexPath which is correct.
I could understand the error if the 3 was out of bounds of my array.count but it definitely isn't.
any ideas?
It seems the issue you are having is with the section and not with the row. Try to build the index like this:
NSIndexPath(item: index, section: 0)
Note the section is set to 0.
There are two options that may be wrong here:
you passed a section that is out of bounds, i.e with index less than 0 or bigger than the specified number of sections in
numberOfSectionsInTableView:(UITableView *)tableView
So just try to use 0 for the section number first.
the index of the row is out of bounds for the specified section (they can be different for each section)
Related
I'm adding data in my model and model is assigned to tableview to reload data. But every time reloading is not looking good. so I want just last element that was added in model, should be appended in already exist tableview. Tried so many ways but getting crash when my tableview is empty.
let lastSectionIndex = self.isGroupChat ? self.objGroupChatList!.count-1 : self.objSingleChatList!.count-1
var lastRow = 0
if self.isGroupChat {
lastRow = (self.objGroupChatList?[lastSectionIndex].count ?? 1)
} else {
lastRow = (self.objSingleChatList?[lastSectionIndex].count ?? 1)
}
let IndexPathOfLastRow = IndexPath(row: lastRow-1, section: lastSectionIndex)
self.tableView.beginUpdates()
self.tableView.insertRows(at: [IndexPathOfLastRow], with: UITableViewRowAnimation.none)
self.tableView.endUpdates()
This is crashing with error:
Terminating app due to uncaught exception
'NSInternalInconsistencyException', reason: 'Invalid update: invalid
number of sections. The number of sections contained in the table
view after the update (1) must be equal to the number of sections
contained in the table view before the update (0), plus or minus the
number of sections inserted or deleted (0 inserted, 0 deleted).'
You should use insertSections for new sections. insertRows only works for existing sections.
You need to do something like,
let section = 0 //get your section here...
dataSource[section].append("five")
let row = dataSource[section].count - 1
tableView.insertRows(at: [IndexPath(row: row, section: section)], with: .none)
This is just an example of how you can get that working. Fill the gaps as per your code.
I have an UITableView, quite standard, with quite dynamic datasource (messages).
To add messages to UITableView I'm using insertRows.
func insertRowsInTableAtIndexPath(ip: IndexPath, right: Bool) {
print("INSERT ROW visible cells: \(tableView.visibleCells.count)\n dispatcher messages \(dispatcher.messages.count)\n numberOfRows \(tableView.numberOfRows(inSection: 0))\n numberOfSections \(tableView.numberOfSections)\n ip: \(ip.row) \(ip.section)")
if tableView != nil {
if right == true {
self.tableView.insertRows(at: [ip], with: UITableView.RowAnimation.right)
} else {
self.tableView.insertRows(at: [ip], with: UITableView.RowAnimation.left)
}
}
print("AFTER INSERT ROW visible cells: \(tableView.visibleCells.count)\n dispatcher messages \(dispatcher.messages.count)\n numberOfRows \(tableView.numberOfRows(inSection: 0))\n numberOfSections \(tableView.numberOfSections)\n ip: \(ip.row) \(ip.section)")
}
It looks pretty standard, because it is. The problem is that in some rare cases (I can replay them but it'd be quite difficult to describe them here) I'm getting the famous NSInternalInconsistencyException: Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (2) must be equal to the number of rows contained in that section before the update (0) and so on.
In these cases the first message is successfully added to the dataSource, and it looks like this message also is inserted as row as well, but it doesn't show up on screen, and the next message is breaking my UITableView because it is invalide update (and it is).
I know that this is happening because of all of these print commands before and after inserting the cell. In bad case these numbers looks like that:
Before inserting the first message:
visible cells: 0
number of messages in dataSource: 1
numberOfRows: 0
numberOfSections: 1
ip: 0 0 (indexPath.row, indexPath.section)
After inserting the first message:
visible cells: 1
number of messages in dataSource: 1
numberOfRows: 1
numberOfSections: 1
ip: 0 0 (indexPath.row, indexPath.section)
At this point I can't see that cell (that was successfully inserted if I could believe UITableView.visibleCells.count)
But if I'm trying to insert the next message, I'm getting an exception. Moreover: UITableView.visibleCells.count is suddenly 0, and numberOfRows is 0 too, although I didn't remove previous row and I didn't remove this message from dataSource.
visible cells: 0
dispatcher messages 2
numberOfRows 0
numberOfSections 1
ip: 0 0
So, I have three questions:
Is it possible for UITableView to not to insert row with insertRows, and how could I prevent this behavior. Why the first row is not showing in the first place?
Why this first row is disappearing from numberOfRows and visibleCells after a while?
What am I doing wrong here?
I understand that this amount of code is not enough to solve this issue from scratch, but this UITableView is pretty standard, and dataSource logic is not so standard and relatively complicated, so my only hope is for people who already have experienced something like that.
update (dataSource methods):
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return dispatcher.messages.count
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
update 2 (the most relevant part of the code):
//this should work when user is changing from one 'chat' to another
//so, first of all, I'm removing all the messages from the dataSource
dispatcher.messages.removeAll()
//also, I'm stopping the timer
if timer != nil {
timer.invalidate()
timer = nil
}
//also, I'm reloading the table with no messages
if tableView != nil {
tableView.reloadData()
}
//after that I'm starting the timer again, and trying to add new messages to the UITableView. The first message is going through (although it is not shown in the UITableView as it should be), the second message is throwing an error because the first row doesn't exist at this point).
let newMessage = dispatcher.giveMeNewMessage()
if newMessage != nil {
dispatcher.messages.insert(newMessage!, at: 0)
let ip = IndexPath(row: 0, section: 0)
insertRowsInTableAtIndexPath(ip: ip, right: false)
self.scrollToRow(ip: ip) //standard scrollToRow
}
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'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
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
}
}