I have a UITableViewController implementing custom cells via
CustomTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
and in the CustomTableViewCell.h file I declared
#property (nonatomic, weak) IBOutlet UISlider *slider;
which is connected to my slider in my storyboard and an IBAction that changes the background of the cell when the slider is adjusted (value changed). My problem is that when I slide down the table view, as soon as my cell is dequeued it is reused with the slider in the same position, and therefore the background an adjusted color. I don't want to keep the entire table in memory, but I need to keep the information input into a cell available for future use. Is there a standard way to handle a problem like this? Thanks.
You can put your slider values into an array, and the dequeueReusableCellWithIdentifier method, you can set the cell slider value from the array
Yes you need to store data for the table in memory (for example slider values in NSArray) and in your UITableView datasource method you need to update state of reused cell. UITableView is smart enough not to load cells for whole table, it loads only visible cells. It is the standard way to do it.
why not configure the cell after method dequeueReusableCellWithIdentifier
cell.backgroundColor = //adjust the color
cell.slider.value = //adjust value
Related
I have a UIButton in a UICollectionViewCell.
When the UIButton is pressed, I clear the selected state and then remove that cell from the UICollectionView using deleteItemsAtIndexPaths. This works perfectly except for one thing.
After the cell is deleted, the cell underneath slides up. That cell's UIButton selected state changes from selected -> unselected. Seems like it's picking up the selected state from the original cell?
Found the problem...
I tried to remove the cell first, but then used the indexpath to unselect the button.
Problem is that because the cell was removed, the indexpath pointed to the cell underneath..
dumb order of operations bug
You should use a model to control the button's state, because the cell will reuse
every cell for indexpath should be binded with a model.
// control button selected state
#property (nonatomic, assign) BOOL isSelected;
cell.button.selected = model.isSelected,
I have a UIViewController with a calendar and below it is a UITableView with a UITableViewCell that has a series of UIButtons that I change the button text depending on the data that I retrieve. When a date is selected I update a NSArray and call [self.tableView reloadData]. The first row populates as it should, the UIButton titles show the correct data. The rest of the rows show the default values for the UIButtons from the storyboard. If I scroll a cell off the screen and let it come back it displays the correct data (i.e. updates the titles of the UIButtons). I'm not sure why this is happening. I tried adding
[cell setNeedsLayout] before the cell is returned but it has not helped.
Are you modifying the testLabels directly? UIButtons have iffy behavior sometimes if you do. Try using the UIButton methods to change the textLabel's properties, such as setTitle: forState:
So i have a custom UITableViewCell which contains three UILabel. The UITableViewCell is such that the UILabel completely cover the cell.
Now i want to detect whenever user taps on the cell. Problem is as the UILabel cover the cell I cannot use UITableView delegate method for detecting touch on the cell.
I thoughout about using gesture recoginzers on the UILabel but then i don't get the index of the touched cell. I also thought about placing a transparent button on top of the cells but here there is also the same problem that i can't get the index of the touched cell.
Can anybody guide me with an approach on how can i accomplish detecting taps with tableView didSelectRowAtIndexPath when UILabel are covering the cell.
Try to set userInteractionEnabled to false in all labels in cell. This will pass touch to the cell and then you can use UITableView delegates. Be sure that cell stays userInteractionEnabled = YES
To get the touch event besides didSelect method try this. In your custom cell class add a block like,
typedef void(^TappedCell)(CustomCell *cell);
and add a property for it,
#property (nonatomic, strong) TappedCell tappedCell;
and on transparent button action
- (IBAction)buttonTapped {
if (self.tappedCell) {
self.tappedCell(self);
}
}
And in cellForRow method
__weak type(self)weakSelf = self;
cell.tappedCell = ^ (CustomCell *tappedCell) {
//Ur actions goes here
//for getting index
NSIndexPath *indexPath = [weakSelf.tableView indexPathForCell:tappedCell];
[weakSelf someActionWithIndexPath:indexPath];
};
It doesnt matter whether UILabel hide your cell or UIImageView hide it. It will automatically detects tableView didSelectRowAtIndexPath. Check it first you wont face any problems. Did you try to implement tableview in detail first
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.
I have a UITableView that I want to alter some of the static cells after I do other processing. I have outlets set up for the cells that I want to modify, but when I look at them using NSLog, they show nil, which indicates to me that I don't have the correct cell. For instance, in the image below I want to add the start time to the label just like I did for Date (date was done when creating the cells for which I got the current date),
I tap on the disclosure indicator which takes me to another scene (this was created in Storyboard, using segues to get from one scene to another) where I get the two times I need. I then return to the main scene (shown) and try to alter the Start Time label, but nothing happens. A NSLog of the label prior to trying to alter it returns this:
oStartTimeCell.textLabel.text: (null)
I have read in one of the Apple docs that this textfield is read-only. If that is true in this case, is there a way I can reload the cells with the updated information? Or is there another way to do this?
You're using the wrong approach. You should not create a reference to a cell using an outlet. Once the cell moves out of the visible view, the outlet will either be null or contain garbage data. Even if (in your situation) the cell will never move out of view, I think it shows you're trying to use a UITableView in a way that was not meant to be.
Instead put the data you want to display in your cells in a dataSource, e.g. an array.
The tableView should use the dataSource to configure the values displayed in the textLabels of the cells. Once you want to update the text displayed in the cells, change the values in the dataSource and call reloadData on the tableView to force the tableView to call -tableView:cellForRowAtIndexPath: and related UITableViewDataSource methods.
Try to create an IBOutlet for each cell and connect it:
IBOutlet UITableViewCell *cell1;
IBOutlet UITableViewCell *cell2;
IBOutlet UITableViewCell *cell3;
And also change your method to:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(indexPath.row == 0) return cell1;
if(indexPath.row == 1) return cell2;
if(indexPath.row == 2) return cell3;
if (cell == nil) {
//create cell;
}
return cell;
}
Are you using a UILabel to display the text ? . If you are just create an outlet to the UIlabel and update it any method like cellForRwoAtIndexPath or didSelectRowAtIndexPath etc that is called after you tableView is loaded.
If you are not using a UILabel and just using cell.textLabel you could do something like
cell.textLabel.text = #"ChangedText" in cellForRowAtIndexPathMethod. Make sure you are editing the required cell by checking indexPath.row
Do [tableView reloadData] to call cellForRowAtIndexPath.