i am using this method to return already created cells in storyboards
" dequeueReusableCellWithIdentifier "
and here is the code
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
switch ( indexPath.row )
{
case 0:
CellIdentifier = #"map";
break;
case 1:
CellIdentifier = #"blue";
break;
case 2:
CellIdentifier = #"red";
break;
}
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier: CellIdentifier forIndexPath: indexPath];
return cell;
}
but i have this error :
'NSInternalInconsistencyException', reason: 'unable to dequeue a cell with identifier map - must register a nib or a class for the identifier or connect a prototype cell in a storyboard'
note: i added the identifiers to storyboard as it is here and it dose not work, another important thing is that : this project was running but now it stopped !!!! I download it from appcoda.com
Here what Apple doc says:
Important: You must register a class or nib file using the registerNib:forCellReuseIdentifier: or registerClass:forCellReuseIdentifier: method before calling this method.
…
Prior to dequeueing any cells, call this method or the registerNib:forCellReuseIdentifier: method to tell the table view how to create new cells. If a cell of the specified type is not currently in a reuse queue, the table view uses the provided information to create a new cell object automatically.
If you previously registered a class or nib file with the same reuse identifier, the class you specify in the cellClass parameter replaces the old entry. You may specify nil for cellClass if you want to unregister the class from the specified reuse identifier.
So you should register your class like this:
- (void) viewDidLoad {
[super viewDidLoad];
[self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:#"map"];
}
Related
I created a UITableViewController of dynamic prototype cells in the Storyboard that can show 3 different custom cells
But I am getting *** Assertion failure in -[UITableView _configureCellForDisplay:forIndexPath:], / which theoretically means that the reuseidentifier I am trying to use in my cellForRowAtIndexPath does not exist but as I am sure I have defined it in my storyboard.
This is my code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
HomeOverviewItem *item = [_items objectAtIndex:indexPath.row];
NSLog(#"cell at %#",indexPath);
if([item propCellType] == HomeOverviewItem_HEADER){
CellHomeHeader *cell = (CellHomeHeader *)[tableView dequeueReusableCellWithIdentifier:#"cell_header"];
cell.propLabelName.text = item.propName;
cell.propLabelCntReqs.text = item.propRequestCnt;
cell.propLabelCntDays.text = item.propDaysCnt;
NSLog(#"returning header cell %#",cell);
return cell;
}else if([item propCellType] == HomeOverviewItem_ITEM1){
CellHomeItem1 *cell = (CellHomeItem1 *)[tableView dequeueReusableCellWithIdentifier:#"cell_item1"];
cell.propLabelName.text = item.propName;
cell.propLabelCntReqs.text = item.propRequestCnt;
cell.propLabelCntDays.text = item.propDaysCnt;
NSLog(#"returning item1 cell %#",cell);
return cell;
}else{
CellHomeItem2 *cell = (CellHomeItem2 *)[tableView dequeueReusableCellWithIdentifier:#"cell_item2"];
cell.propLabelName.text = item.propName;
cell.propLabelCntReqs.text = item.propRequestCnt;
cell.propLabelCntDays.text = item.propDaysCnt;
NSLog(#"returning item2 cell %#",cell);
return cell;
}
}
EDIT:
I will add this image below to make sure that identifier is the same to what I am using on my code
Error:
Where could I possibly go wrong?
I bet your call to dequeueReusableCellWithIdentifier: is returning nil because initially there are no cells to be dequeued (from the docs: A UITableViewCell object with the associated identifier or nil if no such object exists in the reusable-cell queue.). Use
- dequeueReusableCellWithIdentifier:forIndexPath: as this will always return a valid cell.
I found the cause of my problem many thanks to the hint given by Bob....
I want to post this answers for future devs who might also experience this problem.
The one causing this problem is how I instantiate the viewcontroller.
for this case, NEVER instantiate the viewcontrollerv via alloc then init
instantiate the view using [storyboard instantiateViewControllerWithIdentifier:#"yourViewControllerID"]
I am using the code below and getting (Use of undeclared identifier "TableCell")
In the property attribute inspector TableCell is already defined under custom
Any idea?
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"TableCell";
TableCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
// Configure the cell...
int row = [indexPath row];
cell.TitleLabel.text = _Title[row];
cell.Desctiptionlabel.text = _Description[row];
cell.ThumbImage.image = [UIImage imageNamed:_Images[row]];
return cell;
}
If you use the dequeueReusableCellWithIdentifier:forIndexPath: method, you must remember to register the identifier with a class or a NIB first.
That code for your class will probably look something like the following in viewDidLoad, perhaps.
[self.tableView registerNib:[UINib nibWithNibName:"TableCell" bundle:nil] forCellReuseIdentifier:CellIdentifier];
Alternatively, you can use the older dequeueReusableCellWithIdentifier: method, but you will have to handle the case that cell will be nil after dequeue and you will need to load the cell from a nib or instantiate a new object manually.
As an aside, the convention in Objective-C development is to use lower camel case class member names and local variables.
I am trying to build a multilayer xmlparser which shows data in a tableview and switches to the next view based on the selected row (most likely to the same viewcontroller).
I started with storyboard segues but as i am using dynamic cells i dont know how to create more than one push segue (because it needs to push to various viewcontrollers). So i kept the storyboard views, deleted all the segues and used the code below instead.
however it throws this exception when the new view tries to pupulate the row:
Terminating app due to uncaught exception
'NSInternalInconsistencyException', reason: 'UITableView dataSource
must return a cell from tableView:cellForRowAtIndexPath:'
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"index: %i", indexPath.row);
switch (indexPath.row) {
case 0:
{
DetailViewController *detailViewController = [DetailViewController alloc];
[self.navigationController pushViewController:detailViewController animated:YES];
break;
}
//...
default:
{
LayerViewController *layerViewController= [LayerViewController alloc];
[layerViewController setStartUpWithIndex:indexPath.row andLayer:layercount];
[self.navigationController pushViewController:layerViewController animated:YES];
break;
}
}
}
setStartUpWithIndex:andLayer: is my init method...
the problem does not occur when im pushing via storyboard segue with the following segue code:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
[[segue destinationViewController] setStartUpWithIndex:indexPath.row andLayer:layercount];
}
i think i am missing something the "segue" method does which i need to include in my didSelectRowAtIndexPath as cellForRowAtIndexPath: works fine in the first layer of the view.
requested edit:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"LayerCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
cell.textLabel.text = [[articles objectAtIndex:indexPath.row]objectForKey:#"HerstellerName"];
// cell.textLabel.text = #"ololol";
return cell;
}
the articles array is working btw
You aren't creating any cells. I don't know why Apple didn't include this in the default implementation, but after:
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
You need to add:
if (cell==nil){
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
Otherwise you're just relying on dequeued cells which won't exist when the tableView loads.
Edit: And if you're not using ARC, you need to wrap that alloc method with an autorelease.
You are pushing another viewController to be viewed and this next viewController has no dataSource methods implemented. This what happened.
As far as I understood, you are trying to present an xml node with a table in the way that each table row consist child nodes of presented node. selecting row with chld node gets you to next table view which presents table with child nodes of selected node.
IMO you may need only one view controller to present current xml node, which changes only data to be presented in a table and reloads the table again. So no pushing view controllers is needed. You can use then method
– reloadRowsAtIndexPaths:withRowAnimation:
for all the nodes in the table, setting animation similar to changing view controller (aka sliding old table left)
So I've been given an assignment in my Mobile apps class: make a color game app for the iphone.(The description of how to game works is at the top of the pasted viewcontroller.h file below.)
I'm very new to Objective-C and cocoa, but have managed to troubleshoot and fix a lot of things in this app. The problem I have right now is that I don't know how to properly initialize and send UITableViewCells to the view. I'm confused because all of the tutorials I've found online use datasource methods to change different attributes of the UITableView and the cells as well. I'm not sure how these methods will interact with the controls I've already placed. I'm confused because I added them by the storyboard file, not by defining tableview attributes with datasource code.
My immediate issue is that my program won't display the proper text to the cells textlabel and detailtextlabel.
I've looked everywhere online for UITableView and UITableViewCell tutorials, but they are all from years ago and I'm not sure if the advent of the storyboard has changed the way I would treat these controls.
All of the code I've written is either in the viewcontroller.m or viewcontroller.h files.
The method within ViewController.m file, that should call the cell and display text and detail text:
-(IBAction)enterClicked
{
//On enter- send instance colors to the colorTable row[i], perform comparisons and append the resulting symbols to the instanceResults String. Send instanceResults string to the resultTable row[i]. When game counter reaches 6, gameOver. If on comparisons check, the instanceColors are the same as the gameColors, then the player wins.
[self checkForLoss];
if(!self.gameOver)
{
resultOfGuess = [self comparePlayerInputToGameColors:guessColors];
[listOfGuesses addObject:guessColors];
[listOfOutcomes addObject:resultOfGuess];
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:_numberOfTurnsPlayed inSection:0];
UITableViewCell *thisCell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier];
thisCell.textLabel.text = [self.listOfGuesses lastObject];
thisCell.detailTextLabel.text = [self.listOfOutcomes lastObject];
[guessColors setString:#""];
if([self checkForWin:resultOfGuess])
[UpdateLabel setText:#"You have won!"];
else
[UpdateLabel setText:#""];
self.colorCounter = 0;
self.isStepOne = YES;
_numberOfTurnsPlayed++;
}
else
{
if([self checkForLoss])
[UpdateLabel setText:#"You have lost!"];
}
}
The UITableView DataSource Methods I've called at the bottom of the viewcontroller.m file:
#pragma mark - UITableViewDataSource protocol
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
if(section == 0)
return #"Guesses: Results:";
return 0;
}
-(NSInteger) numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
-(NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 6;
}
-(UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier];
}
return cell;
}
So my questions are: Can I change a control's properties with datasource methods, if I created the controls through the storyboard? How do I properly display the text in a uitableview's cells?
Edit/update: Thank you, I've used your advice jrturton, but now I've found something peculiar that may be the source of my problems. in my viewController.h file I've changed my header from
ViewController: UIViewController to ViewController: UITableViewController
Thinking that the datasource methods I call within the viewcontroller files have to be able to call the same methods and properties of the class that I call in the header-- Also, I see this done in other UITableView tutorial files.
The problem is that when I change the header to read-- ViewController: UITableViewController -- and I try to compile, I get this error:
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '-[UITableViewController loadView] loaded the "2-view-3" nib but didn't get a UITableView.'
It compiles fine if I use just :UIViewController in the header file though.
Any ideas?
Further update: I''ve noticed within my storyboard that the only available ViewController object is a UIViewController object, while in the other tutorial files I've seen, this ViewController object is a UITableViewController object. I imagine this is my problem, but I can't seem to switch my UIViewController object to a UITableViewController. All I can do is create a new one, which isn't what I want, I imagine.
Your action method should update the data model (which I think it does, since it changes your listOfGuesses array). You then need to let your table view know that you have added or updated rows so that it can re-load them for you - check the UITableView documentation for reloading data or specific rows.
Creating a cell outside of the datasource methods isn't going to let that cell appear in your table.
At the moment I'm guessing you have 6 empty cells in your table view? You need to populate the text and detail labels in your cellForRowAtIndexPath method. The difference now there are storyboards is that you don't need to do the if (cell == nil) bit, as long as you have set the re-use identifier in your storyboard prototype cell then it will do all that for you. So your cellForRowAtIndexPath method can be reduced to:
-(UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath*)indexPath
{
// This will dequeue or create a new cell based on the prototype in your storyboard
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell"];
// Put your actual configuration here based on your model array
cell.textLabel.text = #"Hello";
return cell;
}
Further hints (this is homework so I'm not giving full samples)
'indexPath.row` in the above method will give you the index from your model array that the cell refers to
You have defined the table as having 6 rows, but you are adding items to your model arrays as you go - so when the table asks for row 5, and your model only has 3 entries, you need to deal with this. Consider changing the number of rows in the table dynamically and using table view methods to indicate that new rows have been added. Again, see the UITableView documentation for this.
Typically the text is set in each cell by accessing the setText property:
[[cell textLabel] setText:#"static string"];
or
[[cell textLabel] setText:someNSString];
or with .dot notation
cell.textLabel.text = someNSString;
return cell;
BTW this is done in the method:
-(UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:
I am trying to populate a TableView situated within a UIViewController with a collection of objects when a button is clicked.
The problem is that cellForRowAtIndexPath seems to be expecting 'votes' to be an instantiated object, which it isn't until the button is pressed.
I'm not sure I'm going about this the correct way and would appreciate any assistance anybody could give me.
I have specified the delegate and datasource as follows:
#interface MyViewController : UIViewController<UITableViewDelegate, UITableViewDataSource>
I have completed my implementation of numberOfRowsInSection as follows:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [self.votes count];
}
I have completed my implementation of cellForRowAtIndexPath as follows:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Votes";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
// Configure the region cell
CandidatePhrase *phrase = [self.votes objectAtIndex:indexPath.row];
cell.textLabel.text = phrase.phrase;
return cell;
}
On button press I'm loading an array with a list of objects
_votes = [[NSArray alloc] initWithObjects:myCandidatePhrase.votes, nil];
I'm just now clear on how the table will bind each time I press the button.
Here's the error I'm currently getting, presumably because the votes array hasn't been instantiated?
2011-12-09 22:34:48.979 MyApp[3809:fb03] -[NSObject tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0x6b49b20
The tableView instance (not the view controller) is going to call its delegate methods as soon as it is instantiated and whenever it is informed of a change to the table view. So it doesn't matter if votes is instantiated or not for the delegate method to be called.
However, if you want it to know that there are no rows when votes has not been instantiated, try this
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
if (votes != nil)
return [self.votes count];
else
return 0;
}
Once you have instantiated votes, you want to call reloadData on your tableView.
Don't forget to add your view controller as the delegate for the tableView, if it is not already.