What I have
1). Container has UITableView, which has two custom UITableViewCells.
2). Core Data has certain entity which has a text to be displayed at
UITableViewCell each time I get into the View.
What i am doing ?
1) I have chosen -viewWillAppear method which gets invoked each time the view is visible.
2) In -viewWillAppear, I retrieved the data from core data.
3) Retrieved particular cell from UITableView
NSUInteger idxArr[] ={2,0}; // 2 nd section, 0th Row.
NSIndexPath *cPath = [NSIndexPath indexPathWithIndexes:idxArr length:2];
myCell *tCell = (myCell *)[self.settings cellForRowAtIndexPath:cPath];
tCell.myLabel.text = rec.servername; // rec.servername is from DC.
When I checked in the lldb,
tCell was nil.
Questions:
1) It is the right way of getting the Cell ?
2) Or, By the time -viewWillAppear, does the UITableView not Ready ?
I am sure.
You should populate the cells by conforming to tableView dataSource protocol and then in your viewWillAppear you should call reloadData on your tableView.
After calling reloadData for tableview, We need to call -scrollToRowAtIndexPath: before getting cell from -cellForRowAtIndexPath:.
Because, As we are calling a row in section 2, it might not be in the visible area until we scroll. So, cellForRowAtIndexPath: returns nil.
Method -cellForRowAtIndexPath: shouldn't be called programically. It's a data source method for UITableView and it contain some cell reuse optimalizations. If you update the view after scrolling down and up -tableView:cellForRowAtIndexPath will be called again and your changes won't be visible.
If you want to update specific cell you should update make changes in:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
YourCell *cell = [tableView dequeueReusableCellWithIdentifier:#"CellId" forIndexPath:indexPath];
YourData *data = //Get your data here
if (data.isReady) {
cell.tf.text = data[indexPath.row].text;
} else {
cell.tf.text = #"Not ready yet. Need to reload this cell later";
}
return cell;
}
And then call method below when you finish fetch your data.
[self.tableView reloadRowsAtIndexPaths:(NSArray *) withRowAnimation:UITableViewRowAnimationFade];
If you want to reload whole tableView (usually it's not slow) as #salaman140 says you can call [self.tableView reloadData] to update all visible cells.
If I were you I wouldn't use:
NSUInteger idxArr[] ={2,0}; // 2 nd section, 0th Row.
NSIndexPath *cPath = [NSIndexPath indexPathWithIndexes:idxArr length:2];
I would (is much more clear):
NSIndexPath *cPath = [NSIndexPath indexPathForRow:0 inSection:2];
Related
I have a tableview in a scrollview in a popover. When the view is presented, the bottom cell in tableview is not visible to the user. If I select all of the cells then deselect the fist cell, the out of view cell is deselected too. Has anyone come across this behaviour before? If so, how to approach it?
Now your job is to find all the visible cells in the tableview and then apply select/deselect to it.
UITableView *tableView = self.tableView;
// Or however you get your table view
NSArray *paths = [tableView indexPathsForVisibleRows];
// For getting the cells themselves
NSMutableSet *visibleCells = [[NSMutableSet alloc] init];
for (NSIndexPath *path in paths)
{
[visibleCells addObject:[tableView cellForRowAtIndexPath:path]];
}
// Now visibleCells contains all of the cells you care about.
-(void) tableView:(UITableView *)tableView didDeselectRowAtIndexPath:
(NSIndexPath *)indexPath {
[tableView deselectRowAtIndexPath:indexPath animated:YES];
}
- (void) tableView:(UITableView *)tableView didSelectRowAtIndexPath:
(NSIndexPath *)indexPath {
//stuff
//as last line:
[tableView deselectRowAtIndexPath:indexPath animated:YES];
}
For that matter, deselectRowAtIndexPath can be called from anywhere at any time you want the row to be deselected.
[self.myTableView deselectRowAtIndexPath:[self.myTableView
indexPathForSelectedRow] animated: YES];
If you are using dequeueReusableCellWithIdentifier: change your cellForRowAtIndexPath: to use dequeueReusableCellWithIdentifier:forIndexPath:
In a UITableView cells get reused. That means it only produces as many as absolutely needed. As soon as a new one is coming onto the screen, the last one is "recycled" instead of initialising a whole new instance.
This makes your application run faster. It also means that you have to undo any changes you made, when recycling.
Selection status is one of them. The UITableView should manage this automatically for you, if it is dequeued with the relevant indexPath. If not, it wouldn't know whether that specific cell should be selected.
I know that dequeueReusableCellWithIdentifier:forIndexPath is called by tableView method inside the tableviewcontroller. And if I understand correctly, tableView method is called several times until all the cells are populated. But what I don't know is where do you get the value for the parameter IndexPath? I want to use dequeueReusableCellWithIdentifier:forIndexPath for a method that I created because I want to access my cell to copy some values of its properties.
NOTE:
I already populated my cell, which means that I successfully used the method tableView.
(Edit) ADDITIONAL INFO:
I'm trying to create a profile and edit profile tableviews. Inside the profile tableview, I displayed the name, address, contact#, etc., of the user. Also, I have a segue called edit profile. In the edit profile, I have textfields for each category (name, address, etc.). What I want to do is, if I edit the contents of the textfields, I should be able to display the new contents in my profile tableview. An example case would be: in the profile view I'm displaying -> name:human, address:earth (each in its own cell). Now if I go to editprofile tableview, I will edit the contents such that -> name:alien, address:mars. After that, there is a button called 'apply' to end editing of contents and go back to profile tableview. If I go back to profile view, the display should now be name:alien, address:mars and not name:human, address:earth.
Here is some code if it's any help. The code is called by a button in tableviewcontroller. "MyCell" is the class of my cell. This code is not working properly. I hope someone can help me fix this.
- (IBAction)updateCopies:(id)sender {
static NSString *ident = #"MyCell";
NSIndexPath *indexPath;
//create cell
MyCell *cell = [self.tableView dequeueReusableCellWithIdentifier:ident forIndexPath:indexPath];
//create variable for accessing cells
int row = [indexPath row];
_labelValues[row] = cell.textField.text
}
You should only use dequeueReusableCellWithIdentifier when you need to supply the table view with a cell to display. If you want to get the UITableViewCell object at a certain index, you should use cellForRowAtIndexPath.
Your problem
What you really need is a model class. You can then pass this to the edit controller, which changes the properties. Then when you return to the tableView, you can reload it and display the new properties.
What you could also do is create a delegate protocol for your edit profile controller, something like EditProfileViewControllerDelegate with something like:
protocol EditProfileViewControllerDelegate {
- (void)editProfileViewController:(EditProfileViewController *)controller didUpdateName:(NSString *)name address:(NSString *)address;
}
You can implement this delegate in your table view controller and use it to update the values when the text is changed. However, this quickly becomes unwieldy, I would not recommend it over using a proper model class.
You can get indexPath using CGPoint..You can use dequeueResusableCell for reusability of the cell..
- (IBAction)updateCopies:(id)sender {
CGPoint position = [sender convertPoint:CGPointZero
toView:self.tableView];
NSIndexPath *indexPath = [self.tableView indexPathForRowAtPoint:position];
//create variable for accessing cells
MyCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
int row = [indexPath row];
_labelValues[row] = cell.textField.text
}
Hope it helps you..
Use this
- (IBAction)updateCopies:(id)sender {
MyCell *parentCell = (MyCell *)sender.superview;
while (![parentCell isKindOfClass:[MyCell 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:(MyCell *)parentCell];
NSLog(#"indexPath = %#", indexPath);
}
Well I got what you want to accomplish.
Firstly, there is a delegate which is being called when you click/select a cell and go to the Edit Profile page. That delegate is
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
///
}
Make a global variable, say selectedIndexPath which holds the current cell index path which is being edited. Update this value each time when you go to edit profile page.
Like this
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
selectedIndexPath = indexPath;
// code to go to edit page...
}
Now in your updateCopies Method, do like this
- (IBAction)updateCopies:(id)sender {
//get the existing cell with the indexPath
[self.tableView beginUpdates];
[self.tableView reloadRowsAtIndexPaths:#[selectedIndexPath]];
[self.tableView endUpdates];
//rest of your code goes here...
}
Edit:
The solution for this answer is related to iOS7 sometimes returning NSIndexPath and other times returning NSMutableIndexPath. The issue wasn't really related to begin/endUpdates, but hopefully the solution will help some others.
All - I'm running my app on iOS 7, and I'm running into problems with the beginUpdates and endUpdates methods for a UITableView.
I have a tableview that needs to change the height of a cell when touched. Below is my code:
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
// If our cell is selected, return double height
if([self cellIsSelected:indexPath]) {
return 117;
}
// Cell isn't selected so return single height
return 58;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
ChecklistItemCell *cell = (ChecklistItemCell *)[self.tableview cellForRowAtIndexPath:indexPath];
[cell.decreaseButton setHidden:NO];
[cell.increaseButton setHidden:NO];
// Toggle 'selected' state
BOOL isSelected = ![self cellIsSelected:indexPath];
DLog(#"%#", selectedIndexes);
DLog(#"is selected: %#", isSelected ? #"yes":#"no");
// Store cell 'selected' state keyed on indexPath
NSNumber *selectedIndex = #(isSelected);
selectedIndexes[indexPath] = selectedIndex;
[tableView beginUpdates];
[tableView endUpdates];
}
The beginUpdates and endUpdates methods are working pretty inconsistently. The didSelectRowAtIndexPath method gets called correctly on each touch(I thought at first the UI was getting blocked), and the selectedIndexes is storing alternating values correctly. The issue is, sometimes I touch a table cell and all the methods are called properly, but the cell height doesn't change. Anyone know what's going on?
There is a change in behavior in iOS7 where index paths are sometimes instances of NSIndexPath and other times UIMutableIndexPath. The problem is that isEqual between these two classes is always going to return NO. Thus, you cannot reliably use index paths as dictionary keys or in other scenarios that rely on isEqual.
I can think of a couple of viable solutions:
Write a method that always returns an instance of NSIndexPath and use it to generate keys:
- (NSIndexPath *)keyForIndexPath:(NSIndexPath *)indexPath
{
if ([indexPath class] == [NSIndexPath class]) {
return indexPath;
}
return [NSIndexPath indexPathForRow:indexPath.row inSection:indexPath.section];
}
Identify rows by the data, not the index path. For example, if your data model is an array of NSString, use that string as the key into your selectedIndexes map. If your data model is an array of NSManagedObjects, use the objectID, etc.
I'm successfully using both of these solutions in my code.
EDIT Modified solution (1) based on #rob's suggestion of returning NSIndexPaths rather than NSStrings.
endUpdates shouldn't be called immediately after beginUpdates. The latter's documentation states, "Begin a series of method calls that insert, delete, or select rows and sections of the receiver." That suggests that it should be called in willSelectRowAtIndexPath: and endUpdates should be called in didSelectRowAtIndexPath.
I need to detect when a tableview has finished reloading data. There was an older solution where you could subclass the tableview then overload the reloadData method, however apparently that no longer works because tables are handled on multiple threads now and reloadData is called before cellForRowAtIndexPath.
My question is, has there been any solution to this problem since the change?
My problem is I am losing the pointer to a textField when the table reloads its data, so the first responder I am trying to set to the next text field (to auto focus on the next data input field), is lost.
This is essentially a repeat of #wain 's answer, but I thought I would add a little code.
You can keep a reference to the index path of the cell that owns the active text field (as a property).
Then, in cellForRowAtIndexPath: something like this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
MyTableViewCell *cell = (MyTableViewCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
//I would hold a reference to the text field as a property on a subclass of UITableViewCell so that you can check for whether it exists.
if (!cell.textField) {
cell.textField = [[UITextField alloc] initWithFrame:cell.contentView.frame];
[cell.contentView addSubview:cell.textField];
}
return cell;
}
- (void)textFieldDidBeginEditing:(UITextField *)textField
{
UITableViewCell *cell = (UITableViewCell *)textField.superview.superview;
NSIndexPath *indexPath = [self.tableView indexPathForCell:cell];
self.indexPathForActiveTextField = indexPath;
}
- (BOOL) textFieldShouldReturn:(UITextField *)textField
{
MyTableViewCell *cell = (MyTableViewCell *)textField.superview.superview;
NSIndexPath *ip = [self.tableView indexPathForCell:cell];
[self.tableView reloadData];
NSIndexPath *nextIndexPath = [NSIndexPath indexPathForRow:ip.row+1 inSection:ip.section];
MyTableViewCell *theNewCell = (MyTableViewCell *)[self.tableView cellForRowAtIndexPath:nextIndexPath];
if (theNewCell) {
[theNewCell.textField becomeFirstResponder];
}
return YES;
}
Store the NSIndexPath of the table cell that holds the text field that should be the first responder. When you want to change the first responder you can ask the table view for the cell at that index path, then find the text field and make it first responder.
If the table view gets reloaded, in cellForRowAtIndexPath: check the index path and make the 'new' text field the first responder.
In this way you can set the first responder at any time and you can't loose the reference to it as the reference is to a location, not an object (which will be reused or removed).
UITableView uses a pool to reuse displayed cell. The target cell is possibly reused in other row. Storing the NSIndexPath like Wain suggested is good untill you not reorder the cells or delete some entry from the datasource. Define a key in the model, that you set the firstResponder according to that. Hope i did not misunderstood the problem.
I have a UITableView with two sections. Based on user interactions (selections and deselections), my datasource and UITableView are updated to move data between sections. Initially their is only data in section 0. When I tap a cell, willSelectCellAtIndexPath and didSelectCellAtIndexPath get called. As expected, when I tap the same cell again, didDeselectCellAtIndexPath is called.
Even after I begin to move data down to section 1 and select and deselect, the UITableView's delegate methods are called appropriately.
Once all data has been moved to Section 1, the UITableView begins to exhibit strange behavior. I can initially select a call and didSelectCellAtIndexPath is called. However, when I tap it again, didDeselectCellAtIndexPath is never called. Instead, any taps on the selected cell (I have confirmed it is indeed selected through [tableView indexPathsForSelectedCells] or any other cells in Section 1 only result in willSelectIndexPath and didSelectIndexPath getting called.
I have quite a bit of code in these delegate methods which is unrelated (I believe).... I do not explicitly change the selected state of a cell anywhere. I have posted willSelect method and can post more if necessary.
- (NSIndexPath *)tableView:(UITableView *)tableView willSelectRowAtIndexPath:(NSIndexPath *)indexPath{
if (remainingItemIsSelected && indexPath.section == 0) {
//other cells in the remaining items section are selected and a cell from that section is being selected
NSMutableIndexSet *arrayIndexesToBeDeleted = [[NSMutableIndexSet alloc] init];
for (NSIndexPath *previouslySelectedIndexPath in [tableView indexPathsForSelectedRows]) {
if (((ReceiptItem *)[self.remainingReceiptItems objectAtIndex:previouslySelectedIndexPath.row]).allocated == YES) {
//update data sources
NSLog(#"%#%i%#,%i",#"Section #:",previouslySelectedIndexPath.section,#" Row #:",previouslySelectedIndexPath.row);
[self.assignedReceiptItems addObject:[self.remainingReceiptItems objectAtIndex:previouslySelectedIndexPath.row]];
[arrayIndexesToBeDeleted addIndex:previouslySelectedIndexPath.row];
//update index path arrays
[self.receiptItemsToDeleteIndexPaths addObject:previouslySelectedIndexPath];
[self.receiptItemsToAddIndexPaths addObject:[NSIndexPath indexPathForRow:self.assignedReceiptItems.count-1 inSection:1]];
//update the pressed indexpath to equal to resulting indexpath to pass on to the didSelect method
if (previouslySelectedIndexPath.row < indexPath.row) {
indexPath = [NSIndexPath indexPathForRow:indexPath.row-1 inSection:0];
}
}
}
//Delete assigned items from the remaining receipt items
[self.remainingReceiptItems removeObjectsAtIndexes:arrayIndexesToBeDeleted];
//update table (move allocated item down)
[tableView beginUpdates];
[tableView deleteRowsAtIndexPaths:self.receiptItemsToDeleteIndexPaths withRowAnimation:UITableViewRowAnimationAutomatic];
[tableView insertRowsAtIndexPaths:self.receiptItemsToAddIndexPaths withRowAnimation:UITableViewRowAnimationAutomatic];
[tableView endUpdates];
if (self.remainingReceiptItems.count == 0) {
[tableView reloadSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationAutomatic];
}
//other cells in the remaining items section are selected and a cell from assigned items is being selected
return nil;
}
return indexPath;
}
From the Documentation for UITableViewDelegate:
tableView:willDeselectRowAtIndexPath:
This method is only called if there is an existing selection when the user tries to select a different row. The delegate is sent this method for the previously selected row.
If you think this through you will find that what you encounter is expected behavior. Tapping a row that is selected does not call will/didDeselctRowAtIndexPath on this row.
Instead, you could handle this in didSelectRowAtIndexPath for the selected row, i.e. deselect it there.
Possible Alternative
That being said, I think you are abusing the UITableView class. It is really not designed to do this moving stuff. You have no doubt noticed yourself that you have to write a lot of code to make this work -- the very reason you are encountering intractable errors.
It seems to me that a much cleaner (and ultimately more flexible) solution would be to have two separate table (or other) views that notify each other via delegates about datasource changes. Maybe a bit more work setting it up, but surely much less trouble down the road.