I have an application with a UICollectionView with horizontal scroll of cells (Only one cell is displayed at a time). Each cell hosts a UITableView which displays content (URL links) in each of the UITableViewCell.
The problem is that the first two cells of UICollectionView display the proper content, but starting from the third cell, the contents are displayed from the dequeued cells. The correct content on the dequeued cell's UITableView is only displayed if user scrolls down and then scrolls up to the top.
For example, the contents of the third cell are the content from the first cell.
The cell is a custom UICollectionViewCell that hosts the UITableView. The custom cell implements the UITableViewDataSource, UITableViewDelegate.
I have searched through different forums and sites and found the solution of refresh.
I tried adding the [collectionView reload] to the -cellForItemAtIndexPath: method, but it goes into constant loop. I know that is not the right place, but i do not have any other methods that cause the refresh (only scrolling through the cells loads the next cell's content).
Can somebody please help me to resolve the issue?
You are missing some facts about dequeuing.
When you 3d custom UICollectionViewCell is dequeued, it isn't allocated like when it's displayed for the first time. Instead, your collection view "reuses" 1st cell for displaying 3d. The best moment to clear content in your custom cell class is -(void)prepareForReuse. If you override it and clear it's content, the -cellForItemAtIndexPath: will dequeue "clear" cell which you can further customize.
However, i don't exactly know how to "clear" the tableView, not sure whether it's possible. You have to reloadData on your tableView in -cellForItemAtIndexPath:. Example:
- (UICollectionViewCell*)collectionView:(UICollectionView*)collectionView cellForItemAtIndexPath:(NSIndexPath*)indexPath
{
MyCVCell *cell = [collectionView dequeueReusableCellWithIdentifier:#"MyCVCell" forIndexPath:indexPath];
cell.arrayOfURLsForDisplay = self.arrayOfArraysOfURLs[indexPath.row];
[cell.tableView reloadData];
return cell;
}
Here i mean you have some arrayOfArraysOfURLs in your viewController and you dislay URLs in your custom cell from some arrayOfURLsForDisplay
I had similar problem, instead of using [cell.tableView reloadData] inside the cellForItemAtIndexPath, I called collectionView.reloadData in the prepareForUse method that is overwritten in your custom UITableviewCell
Related
I have webview in table view cell , whenever tableview cell is scrolling ,Web view reloads ....How to stop webview reload while tableview is scrolling.
Hi iOSDev please follow the following link
Don't reuse cell in UITableView
Max Pevsner solution fulfills your problem of not dequeuing the cell with just instantiating a table view cell.
But my suggestion is you use static webView, instead of not dequeuing the cell, as it will always stay in memory till the tableview is loaded, and moreover every time the cell will be created again when you will scroll the tableview. not dequeuing cell will be least efficient, for the tableview.
The situation is pretty simple (as pretty common as I thought). I have an UITableView in my application that has lets say 3 rows (all are visible on the screen). Next I tap on one of them and this action changes something in all three cells (e.g. change scale of some UIView that is in this every cell) and everything is ok.
This is ok until I have only visible cells on the screen. I know that cellForRowAtIndexPath works only for visible cells. So how can we change such kind of properties (not data properties) for all the cells?
cellForRowAtIndexPath is where you prepare the cell for display. You should be doing the changes in here.
How are you modifying the view scale inside the cells when the user taps on a cell?
You should be triggering a reloadData() on the tableview which will reload the tableview and trigger the cellForRowAtIndexPath calls. You can also reload specific indexes inside the tableview if needed.
Inside your cellForRowAtIndexPath you should use some logic or state variable to control how you configure your cell. Dont dump all the code inside that function, pass arguments to your cell in a function e.g configureCell(subviewScale: CGFloat) and let the cell configure itself.
Dont forget to reset the scale of the subview in prepareForReuse() on your custom cell so that when the cell is about to be dequeued and reused, it gets its properties reset.
I have a custom table view cell. I have a UIView in the tableview cell that is shown only when the table is expanded. I toggle the height for table view cell each time on tap to show the UIView. I also need to detect clicks on some of the components of UIView.
->tablecell1
-->UIView1 height h1
->tablecell2
-->UIView2 height h2
The cell height of the cell should vary according to the size of UIView. Currently I am calling
tableView:heightForRowAtIndexPath: for varying the height on cell click. However this doesn't work if the UIViews are of variable heights and the bigger view gets clipped.
Is there a better way of solving it?
Ok so real quick tableView:heightForRowAtIndexPath: shall not be called by your controller.
The biggest problem I always run into when dynamically sizing cells is that that heightForRowAtIndexPath is called very early on in the table layout process, so essentially the height of each cell must be know prior to asking the tableview to layout. Anyway I am going to assume that you are using a custom table view cell and have placed a UIView inside there... If you haven't, do.
First: Throw a class function into the CustomTableViewCell called heightNeededForTableViewCellWithView:(UIView *)view and determine the height you would want, handle the condition where view is nil and what the default size shall be.
Second: Call this class function when tableView:heightForRowAtIndexPath: is called and since you own the datasource in your controller you can dynamically return the heightNeededForTableViewCellWithView:viewAtRow based off the view you would want to show for that row!
Third: When a user taps a cell, remember which index they tapped and call [tableView reloadData] which will call tableView:heightForRowAtIndexPath:
For reference, this tutorial I am following: http://mobile.tutsplus.com/tutorials/iphone/customizing-uitableview-cell/
I have to create a custom UITableViewCell, and from the tutorial, it said to leverage Prototyping cells and subclass UITableViewCell. Then connect the UI elements in the prototype cel to the custom class (of UITableViewCell).
The problem I am running into here is, there is only one cell for the whole table view that is displaying data. However, I am able to click on empty cells in the background behind that one cell that contains data. If i scroll up or down, cellForRowAtIndexPath is called and another cell gets displayed. However its only displaying once cell at a time for the whole table view.
Does anyone know what the problem could be here? Any help is appreciated, thanks!
Figured out what the problem is, my labels (that are supposed to be inside the custom prototyping cell) were added to the parent view and not the content view of UITableViewCell. This is because my prototype cell did not have a content view for some reason. I had to add a another prototype cell and delete the previous one.
reference: How to add subviews to a custom UITableViewCell in a storyboard
I'm trying to resize a UITableViewCell without reloading the table view.
My UITableViewCell contains a UITextView so users can input list items that may be several lines (about four max) in length. Right now, I'm resizing the text view each time the user presses the return key, but I'd like to change the height of the table view cell as well.
The main problem I'm running into is that reloading the table view's data makes the text view lose focus. Is there any way to change the height of the UITableViewCell without reloading the table view, letting the user continue to input text in the text view?
To resize a table view row, try sending:
[tableView beginUpdates];
[tableView endUpdates];
These messages one immediately after the other should do the trick provided you have the correct height returned for that cell in the tableView:heightForRowAtIndexPath: method. The row should animate. You should be able to return the height of your cell using its bounds or just from knowing what you've set the cell height as.
Obviously "tableView" is the name of your table view.