I'm having a perplexing problem with a simple UILabel I put on a cell in a UITableView. I enter a separate view after tapping on a row, like many UITableViews. In there, I update the cell so that when I return to the rows, it should be updated, with this:
MyTableViewCell* cell =
(MyTableViewCell*) [mTableView cellForRowAtIndexPath:
[NSIndexPath indexPathForRow:mActiveRow inSection:0]];
cell.myLabel.text = #"New Value"; // updated text
cell.myLabel.backgroundColor = [UIColor greenColor]; // updated color
When I return, though, only the text is updated, not the color. When I scroll the row off the screen and return it refreshes properly via another path of code that has exactly the same code. Could there be some trigger to refresh specifically the background color of the UILabel? I'm not sure why the text will refresh but the color won't.
Neeeeeeevermind. I had overlooked the [TableView reloadData] method to refresh the cells. That worked perfectly.
Related
I'm trying to change the background color of the Footer of a UITableView section. However, I'm not having any luck.
UITableViewCell *cell = [_tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:i]];
cell.backgroundColor = [UIColor redColor];
cell.textLabel.textColor = [UIColor redColor];
cell.detailTextLabel.textColor = [UIColor redColor];
UITableViewHeaderFooterView *header = [_tableView footerViewForSection:i];
[header setBackgroundColor:[UIColor redColor]];
The first part - where I set the colors in the cell - is working. The second part - where I want to set the footer color - isn't. What am I doing wrong?
You need to set the color inside the cellForRowAtIndexPath method and inside the footerViewForSection method.
The table view will request cells, headers and footers as it needs them. For cells, chances are it will reuse the same cell which is why you cell color seems to work. However if you do some scrolling you will find it probably stops working.
Your header view does not work because you are asking for a view in your code, but that will not be the same view the table uses as it will have asked for its own.
So you should set the colors when the cell, header or footer is being requested.
Ideally the cell/header/footer configurations should be driven from your data model. e.g. Inside cellForRowAtIndexPath, you should create the cell appropriate for the data model entry for the index path. Sets its color based on the color required by the data model entry. All changes then are done on the data model and you reload the affected sections and/or rows.
Is -footerViewForSection: returning a value? My guess is it's returning nil. Are you providing the footer view to the table view in the delegate methods? If you're not, it doesn't exist. If you are, you can set the color then.
I changed the color of text for the cell clicked in the table. But after the cell is clicked, when i come back to table the text of cell has the original color. Could you give me an advice?
This is the code in "didSelectRowAtIndexPath"
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
cell.textLabel.highlightedTextColor = [UIColor blueColor];
Thank you
after the cell is clicked, when i come back to table the text of cell has the original color. Could you give me an advice?
You need to have the color for each cell stored somewhere other than in the table, so that you can reproduce the colors you want anytime the table redraws itself. Typically, you'll have some sort of data structure that stores the table's data, and that's usually the right place to save any changes the user makes. The table view's data source should have a -tableView:cellForRowAtIndexPath: method that sets the color according to what you've saved, along with any other cell attributes.
This is happen because the cells are reused, so lets say when you change text colour property of some cell it will be affected as you expect but when you scroll and that cell disappear off the screen it will be put to reuse pool and if it appears again on the screen table view takes some cell from the reuse pool but it's properties will be different so the colour won't persist.
You should keep somewhere, for example in NSMutableArray, info about which table was clicked.
You can add an index path to the array when you click the cell and in cellForRowAtIndexPath: check is this indexPath in the array and if it is change appropriate property.
The problem is that iOS throws away your cell if you scroll away and recreates it when it's needed (you scroll back to the cell).
If I were you, I would subclass UITableViewCell and overwrite
- (void)setSelected:(BOOL)selected animated:(BOOL)animated;
In there you would have
- (void)setSelected:(BOOL)selected animated:(BOOL)animated
{
[super setSelected: selected animated: animated];
self.textLabel.textColor = selected ? [UIColor blueColor] : [UIColor blackColor];
}
Since iOS UITableView remembers which cell is selected, this should work fine, even when it's recreated.
The reason it's happening is what others are saying: cells are reused.
Storing selection state or color will work, however if you just need to make sure that selected cells have a different color for a label than non-selected cells, there's a way that does not require to use a supporting data structure.
You just need to check if the cell being setup at - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath is currently selected or not, and that can be achieved with [tableView indexPathForSelectedRow] if your table uses single selection, or [tableView indexPathsForSelectedRows] if it uses multiple selection.
The last case requires you to find the current indexPath in the returned array, and might be slower than using the supporting array.
But if the selection is simple, then this solution is probably faster, uses less memory and is easier to read (IMO).
I've got a UITableView with several different elements added programmatically. The one I'm having trouble with is the UITextView that displays correctly with correct color, size, font, etc... I have a button in one cell that increases the size of the font in the UITextView in another cell. It works fine and has no issues. The numerical value is placed in a Plist, and when you leave the view with the table and come back the size changes perfectly.
I've placed a reloadData in the button which does reload the table and gives the textView new size and resizes it to fit the new content plus resizes the cell perfectly. The issue I'm having is that when the reloadData is called, the old textView remains. So I have two texts, at two different sizes, or three or four and so on. How can I remove the previous textView when it's not set to global?
Everything is set up exactly how one would expect:
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell" forIndexPath:indexPath];
// cell with textView. Everything is instanced and created for just that cell with tags
UITextView *t = [self setSizeAndTextOfTextView];
[cell.contentView addSubview:t];
// cell with button. simple, alloc's and init inside cell. Calls method in same class
cell.contentView addSubview:button];
//method to increases font size
write to Plist the new size
[self.tableView reloadData]; <-- tableView is iboutlet that does reload table
How are you getting the cell in the first place? Are you reusing? If you are you don't want to add the textview as a subview again you want to retrieve the existing one and adjust it
UPDATE:
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell" forIndexPath:indexPath];
if ([cell.contentView viewWithTag:1]) {
UITextView *t = (UITextView *)[cell.contentView viewWithTag:1];
//This version will take an existing textview and just resize it
[self setSizeAndTextOfTextView:t];
} else {
//This version creates a new text view
UITextView *t = [self setSizeAndTextOfTextView];
t.tag = 1
[cell.contentView addSubview:t];
}
You'll probably need to do something similar with you button as well
The reloadData won't wipe the existing cells, just the data displayed, so you'll get an old one to reuse
You may consider creating a custom subclass of UITableViewCell and associate that with your cell identifier. In your subclass, override the prepareForReuse method to set the cell back to a neutral state. Since cell objects are reused but are only initialized once, prepareForReuse is available to restore an already existing cell to its freshly initialized state.
My UICollectionView's cells have a contentview with a background color of white upon loading. Users can change the background color of the cell's contentview to cyan by selecting the cell assuming a boolean value (isSplitting) is set to YES.
My problem arises when I have more cells then fit on the screen and the user has selected cells and thus changed their contentview's background color to cyan.
I have instances where cells that are cyan get scrolled out of view and when scrolled back in are white. I also have instances where cells that are not cyan are scrolled into view and are cyan.
I understand that the cells are being dequeued for reuse and retaining their background colors when getting loaded into a different indexpath.
I have resolved the issues of cells that are not selected becoming cyan upon scrolling into view. I have not however been able to resolve the issue of certain selected cells losing their cyan color when scrolled in and out of view.
Here is the current logic I have in cellForItemAtIndexPath.
if (!isSplitting) {
cell.contentView.backgroundColor = [UIColor whiteColor];
}
else{
for (NSIndexPath *collectionIndexPath in [self.myCollectionView indexPathsForSelectedItems]) {
if (indexPath == collectionIndexPath) {
cell.contentView.backgroundColor = [UIColor cyanColor];
break;
}
else{
cell.contentView.backgroundColor = [UIColor whiteColor];
}
}
}
I know the that correct cells are indeed selected because another operation using the same for loop above produces the desired results. The logic seems to breakdown if I select the first couple items (turn them to cyan), scroll to the right and select the 10th item. When I scroll back to the left the first couple are still cyan but upon scrolling to the right again the 10th is back to white.
Use isEqual: to compare the indexPaths rather than ==
if ([indexPath isEqual:collectionIndexPath]) {
I have a UITableview cell that gets a tally from a core data database. The tallyTable is in a view controller inside a UITab view. I have an NSLog statement that prints out the tally value whenever it gets updated. Another tab has a list to change the source (different day) for the tallies. I am using iOS5 with ARC targeting iOS 4.2.
Here's the problem. When I load the application, the correct tallies for whatever the last selected day show up in the table tab. If I then go to the day tab and change the day and return to the tally tab there is no change in the display. However, the viewWillAppear on the tally tab runs and as the table cycles through cellForIndexPath, my NSLog statement prints out all the correct new values. If I then scroll the top label off the screen and back the label updates to the new value.
I've tried setNeedsLayout and setNeedsDisplay on the UILabel, the UITableViewCell, the UITableView and the view controller loading the table. I tried changing the CellReuse identifier so that it would never reuse a cell.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
CollectionItemTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[CollectionItemTableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
NSUInteger row = [indexPath row];
cell.textLabel.text = [[self.collectionKeys objectAtIndex:row] valueForKey:#"collectionTitle"];
NSInteger test1 = indexPath.row + 150;
NSLog(#"tag = %i", test1);
cell.tallyButton.tag = test1;
NSNumber * questionID = [[self.collectionKeys objectAtIndex:row] valueForKey:#"answerID"];
cell.tallyLabel.text = [NSString stringWithFormat:#"%i",[self updatePointTotal:questionID]];
NSLog(#"Collection text should be = %#", [NSString stringWithFormat:#"%i",[self updatePointTotal:questionID]]);
[cell setNeedsLayout];
return cell;
}
I've read over a half dozen other similar questions. Got about three hours invested so far in trying to solve this.
EDIT: I thought I fixed it by using the navigation controller to repush the top level view controller on to the view again. I'll admit now this feels like a classically kludgy hack in every way. When the view is PUSHED everything updates and it is seamless. However, in order to have a fixed footer to make selection settings for the table buttons, I used a UIView with two subviews, a UITableView on top and a simple UIView with four buttons below.
The captions on the buttons need to change with the data source. Now when the view controller is pushed onto the view it obscures my fixed footer view. So, I inserted the fixed footer into the UITableview and everything appeared fine until I scrolled the UITableView and the footer scrolled up with it. The table is basically a tally sheet with buttons next to each item and in the footer is four buttons to note the color of the tallied item. Say the next item was a green lego, you would tap "green" in the footer and the button next to "lego" in the table. When I push the view controller with the two subviews the UITableview labels do not update. Thus the tableview needs to be pushed itself (as far as I can tell).
ANSWER: see comment below but ultimately I needed to reload both the visible UITableView data and the delegate UITableView controller data behind it.
I'll give it a shot. First, are you using ARC? If not, you need to add autorelease when you alloc/init a new cell. Otherwise, it's fine as is.
If I'm understanding your question correctly:
The tableView displays the correct data at app launch
You switch away from the tab with the tableView and change the tableView dataSource
You switch back to the tab with the tableView and you see (via NSLog) that the table cells are reloaded with the correct data yet the old data is still visible in the cells
If you scroll a cell off the display and back forcing it to refresh it contains the correct data
Some thoughts:
the tableView will not reload itself automatically when it's view appears. You need to call [tableView reloadData] whenever the dataSource changes. This is independent of whether the tableView is currently displayed or not. My guess is this alone will solve your problem.
You don't need to call setNeedsLayout on the cell unless you want the cell to relayout its subviews based on the data. You also don't need setNeedsDisplay.
I'm assuming there aren't other complicating factors (such as multiple tableViews displaying the same data) that could confuse things.
If you use prepare for reuse method, remember to over the original method with [super prepareForReuse];
Another method if the above way does not work is re setup cell as describe here.
I use the same method i applied for some of my collection view : we should remove/reset your subview where you create/add it to cell 's content. That mean we need set up data each cell completely for each row.
I move the code reset data value from prepare reuse to where i set value and I worked simply !
In my CustomCell.m :
- (void)configCellWith:(id)item At:(NSUInteger)row {
if (_scrollView) {
[[_scrollView subviews]
makeObjectsPerformSelector:#selector(removeFromSuperview)];
_scrollView = nil;
[_scrollView removeFromSuperview];
}
else {
CGFloat y = labelHeight+15;
float scrollHeight = _imgArray.count*200;
_scrollView=[[UIScrollView alloc]initWithFrame:CGRectMake(10, y,SCREEN_WIDTH-20, scrollHeight)];
_scrollView.scrollEnabled=YES;
_scrollView.userInteractionEnabled=YES;
_scrollView.layer.masksToBounds = YES;
[self.contentView addSubview:_scrollView]; } }
Remember to change your data source appropriately too.