i am confused about indexPath and indexPath.row, does each cell of a tableView correspond to an indexPath? so why do we look for the "row" of this indexPath? i checked the doc but i think it confuses me.
i found this code :
// this method is used in case the user scrolled into a set of cells that don't have their app icons yet
- (void)loadImagesForOnscreenRows
{
if ([self.entries count] > 0)
{
NSArray *visiblePaths = [self.tableView indexPathsForVisibleRows];
for (NSIndexPath *indexPath in visiblePaths)
{
AppRecord *appRecord = [self.entries objectAtIndex:indexPath.row];
if (!appRecord.appIcon) // avoid the app icon download if the app already has an icon
{
[self startIconDownload:appRecord forIndexPath:indexPath];
}
}
}
}
Can you explain me the difference between the two?
Thanks a lot
Paul
Each instances of NSIndexPath class has two properties: row and section (Documentation)
Each cell of tableView corresponds to unique indexPath (N-th row in M-th section). Often there is only one section and people use only row to reference to the data.
Related
I can't get out of this, I have a UICollectionView with custom cell and every cell has a X button to delete it from the list, I pass to the button.tag the IndexPath.item and on the delete function i've implemented the following method:
- (void)DeleteProductFromArray:(UIButton *)button {
NSLog(#"item: %d",button.tag);
TagHelpConverted = [NSNumber numberWithInt:button.tag];
TagHelp = button.tag;
if(DeletedCells.count == 0)
{
[DeletedCells addObject:TagHelpConverted];
}
else
{
for(int i = 0; i < DeletedCells.count; i++)
{
if([TagHelpConverted compare:DeletedCells[i]] == NSOrderedDescending)
{
TagHelp--;
NSLog(#"ho diminuito il tag di 1");
}
}
[DeletedCells addObject:TagHelpConverted];
}
NSLog(#"valore tagHelp:%d", TagHelp);
[_feedItems removeObjectAtIndex:TagHelp];
[self.customCollectionView deleteItemsAtIndexPaths:#[[NSIndexPath indexPathForItem:TagHelp inSection:0]]];
[self.customCollectionView reloadData];
}
The problem is that when scrolling the UICollectionView calls the - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath { and my NSMutableArray that stores which button has already been clicked has "old values" that compared to the new ones assigned by this method makes the app delete random items inside the UICollectionView.
I searched on the Internet for help about deleting UICollectionView cells but I found almost anything, I'm struggling very hard on this one but I can't find a way to get out, please if anyone has a solution help me
To delete cells from a collectionView you can remove them from the data source and reload the collectionView. You want to make sure you keep your data source in sync with what is on the screen. Basically, keep your data source how you want it and call [collectionView reloadData].
- (void)didTapDeleteCellBtn:(UIButton *)deleteCellBtn {
UICollectionViewCell *cell = (UICollectionViewCell *)deleteCellBtn.superview.superview; // Make sure this gets the right cell for the button
NSIndexPath *indexPath = [self.customCollectionView indexPathForCell:cell];
id item = self.feedItems[indexPath.row];
NSMutableArray *updatedFeedItems = [self.feedItems mutableCopy];
[updatedFeedItems removeObject:item];
self.feedItems = [NSArray arrayWithArray:updatedFeedItems];
[self.customCollectionView reloadData];
}
I have an iPad app (XCode 4.6, ARC, Storyboards, iOS 6.2.3). I have a UIPopover with a UITableView that has 21 rows in it. I can set the accessoryType in all of the rows randomly, but only in the first 12 rows does the accessoryType setting (checkmark) persist so it can be examined in another method and processed. I don't see any difference between the first 12 rows and the last 9 rows. The UITableView is scrollable, so to get to the rows after the 11th row, you have to scroll to the bottom
Here is the code to set the accessoryType:
#pragma mark didSelectRowAtIndexPath
- (void) tableView:(UITableView *) tableView didSelectRowAtIndexPath: (NSIndexPath *)indexPath {
// get the cell that was selected
UITableViewCell *theCell = [tableView cellForRowAtIndexPath:indexPath];
if(theCell.accessoryType != UITableViewCellAccessoryCheckmark)
theCell.accessoryType = UITableViewCellAccessoryCheckmark;
else
theCell.accessoryType = UITableViewCellAccessoryNone;
}
Here is the code where I check the accessoryType and process it:
-(void) moveServices { // (moves checked tableViewRows to services tableview)
NSMutableString *result = [NSMutableString string];
for (int i = 0; i < [servicesArray count]; i++) {
NSIndexPath *path = [NSIndexPath indexPathForRow:i inSection:0];
[tvServices scrollToRowAtIndexPath:path atScrollPosition:UITableViewScrollPositionMiddle animated:NO];
UITableViewCell *cell = [tvServices cellForRowAtIndexPath:path];
if (cell.accessoryType == UITableViewCellAccessoryCheckmark) {
[result appendFormat:#"%#, ",cell.textLabel.text];
NSLog(#"\n\ni: %d\ncell.accessoryType: %d\ncell.textLabel: %#",i,cell.accessoryType, cell.textLabel);
}
}
if (result.length > 2) { // move to text box in main menu
storeServices =[result substringToIndex:[result length] - 2];
}
}
It looks like you're mixing the notion of "data source" and the contents of the cells in the table. Don't do that -- keep your data source (whether or not a particular row in the table should display a checkmark based on your program logic) separate from the settings of particular cells (whether or not a particular cell displays a checkmark). Then in cellForRowAtIndexPath, you build the cell to match your data source's current settings. The reason is that UITableView reuses cell instances based on which rows are visible on-screen (and it's just good MVC design).
In your case you should keep an NSMutableArray property in your class that records the settings for the entire table, and use the value from that array in cellForRowAtIndexPath to set up that particular cell. Then the other "business logic" methods in your controller use the array property to query your model state instead of the cell settings (which are part of the view and should be independent from the data model).
I have a UITableView made of static cells, and each cell contains a UILabel which is populated with field data when the screen loads. There are more cells than can fit on one screen, so the table view scrolls. The UILabels are hidden at design-time and I want to set them visible once all the text properties have been set. I've been using the subviews property of the tableView to iterate through the labels to setHidden:NO but this only affects the labels within cells that are currently in view. How can I iterate through all the UILabels regardless of which ones are in view or not?
Thanks
Jonathan
You can address this issue inside your tableView:cellForRowAtIndexPath: method.
Assuming that you have implemented your static cells the way Apple's guide suggests, your tableView:cellForRowAtIndexPath: should look like a sequence of if-then-else statements returning the cells provided through IBOutlet objects:
if (indexPath.row == 0) {
return cell1;
} else if (indexPath.row == 1) {
return cell2;
} // .. and so on
Modify this code as follows:
UITableViewCell *res = nil;
if (indexPath.row == 0) {
res = cell1;
} else if (indexPath.row == 1) {
res = cell2;
} // .. and so on
// Call your custom code that makes the label visible
if (allTextPropertiesHaveBeenLoaded) {
[res setMyLabelVisible];
}
return res;
When all text properties have been set, call reloadData to force all cells to go through your tableView:cellForRowAtIndexPath: and get reconfigured.
just call upon the cellForRowAtIndexPath: method
for(NSUInteger i = 0; i < numberOfCells; i++) {
UITableView* cell = [tableView cellForRowAtIndexPath: [NSIndexPath indexPathForRow:i inSection:0];
}
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 have a tableview controller that displays a row of cells. Each cell has 3 buttons. I have numbered the tags for each cell to be 1,2,3. The problem is I don't know how to find on which cell a button is being pressed. I'm currently only getting the sender's tag when one of the buttons has been pressed. Is there a way to get the cell row number as well when a button is pressed?
You should really be using this method instead:
CGPoint buttonPosition = [sender convertPoint:CGPointZero toView:self.tableView];
NSIndexPath *indexPath = [self.tableView indexPathForRowAtPoint:buttonPosition];
Swift version:
let buttonPosition = sender.convert(CGPoint(), to:tableView)
let indexPath = tableView.indexPathForRow(at:buttonPosition)
That will give you the indexPath based on the position of the button that was pressed. Then you'd just call cellForRowAtIndexPath if you need the cell or indexPath.row if you need the row number.
If you're paranoid, you can check for if (indexPath) ... before using it just in case the indexPath isn't found for that point on the table view.
All of the other answers are likely to break if Apple decides to change the view structure.
Edit: This answer is outdated. Please use this method instead
Try this:
-(void)button1Tapped:(id)sender
{
UIButton *senderButton = (UIButton *)sender;
UITableViewCell *buttonCell = (UITableViewCell *)[senderButton superview];
UITableView* table = (UITableView *)[buttonCell superview];
NSIndexPath* pathOfTheCell = [table indexPathForCell:buttonCell];
NSInteger rowOfTheCell = [pathOfTheCell row];
NSLog(#"rowofthecell %d", rowOfTheCell);
}
Edit: If you are using contentView, use this for buttonCell instead:
UITableViewCell *buttonCell = (UITableViewCell *)senderButton.superview.superview;
I would recommend this way to fetch indexPath of cell which has any custom subview - (compatible with iOS 7 as well as all previous versions)
-(void)button1Tapped:(id)sender {
//- (void)cellSubviewTapped:(UIGestureRecognizer *)gestureRecognizer {
// UIView *parentCell = gestureRecognizer.view.superview;
UIView *parentCell = sender.superview;
while (![parentCell isKindOfClass:[UITableViewCell class]]) { // iOS 7 onwards the table cell hierachy has changed.
parentCell = parentCell.superview;
}
UIView *parentView = parentCell.superview;
while (![parentView isKindOfClass:[UITableView class]]) { // iOS 7 onwards the table cell hierachy has changed.
parentView = parentView.superview;
}
UITableView *tableView = (UITableView *)parentView;
NSIndexPath *indexPath = [tableView indexPathForCell:(UITableViewCell *)parentCell];
NSLog(#"indexPath = %#", indexPath);
}
This doesn't require self.tablview either.
Also, notice the commented code which is useful if you want the same through a #selector of UIGestureRecognizer added to your custom subview.
There are two ways:
#H2CO3 is right. You can do what #user523234 suggested, but with a small change, to respect the UITableViewCellContentView that should come in between the UIButton and the UITableViewCell. So to modify his code:
- (IBAction)button1Tapped:(id)sender
{
UIButton *senderButton = (UIButton *)sender;
UITableViewCellContentView *cellContentView = (UITableViewCellContentView *)senderButton.superview;
UITableViewCell *tableViewCell = (UITableViewCell *)cellContentView.superview;
UITableView* tableView = (UITableView *)tableViewCell.superview;
NSIndexPath* pathOfTheCell = [tableView indexPathForCell:tableViewCell];
NSInteger rowOfTheCell = pathOfTheCell.row;
NSLog(#"rowofthecell %d", rowOfTheCell);
}
If you create a custom UITableViewCell (your own subclass), then you can simply call self in the IBAction. You can link the IBAction function to your button by using storyboard or programmatically when you set up the cell.
- (IBAction)button1Tapped:(id)sender
{
UITableView* tableView = (UITableView *)self.superview;
NSIndexPath* pathOfTheCell = [tableView indexPathForCell:self];
NSInteger rowOfTheCell = pathOfTheCell.row;
NSLog(#"rowofthecell %d", rowOfTheCell);
}
I assume you add buttons to cell in cellForRowAtIndexPath, then what I would do is to create a custom class subclass UIButton, add a tag called rowNumber, and append that data while you adding button to cell.
Another simple way:
Get the point of touch in tableView
Then get index path of cell at point
The index path contains row index
The code is:
- (void)buttonTapped:(id)sender {
UITapGestureRecognizer *tap = (UITapGestureRecognizer *)sender;
CGPoint point = [tap locationInView:theTableView];
NSIndexPath *theIndexPath = [theTableView indexPathForRowAtPoint:point];
NSInteger theRowIndex = theIndexPath.row;
// do your stuff here
// ...
}
Swift 3
Note: This should really go in the accepted answer above, except that meta frowns upon such edits.
#IBAction func doSomething(_ sender: UIButton) {
let buttonPosition = sender.convert(CGPoint(), to: tableView)
let index = tableView.indexPathForRow(at: buttonPosition)
}
Two minor comments:
The default function has sender type as Any, which doesn't have convert.
CGPointZero can be replaced by CGPoint()
One solution could be to check the tag of the button's superview or even higher in the view hierarchy (if the button is in the cell's content view).
I would like to share code in swift -
extension UITableView
{
func indexPathForCellContainingView(view1:UIView?)->NSIndexPath?
{
var view = view1;
while view != nil {
if (view?.isKindOfClass(UITableViewCell) == true)
{
return self.indexPathForCell(view as! UITableViewCell)!
}
else
{
view = view?.superview;
}
}
return nil
}
}
In swift:
#IBAction func buttonAction(_ sender: UIButton) {
guard let indexPath = tableView.indexPathForRow(at: sender.convert(CGPoint(), to: tableView)) else {
return
}
// do something
}