I'm having some issues with reusable cells in a UITableView. I have several types of cells, that I declare in the constructor.
My issue is that I have one particular type of cell that contains a UITextView and I have an issue when I scroll the table, the text within is lost. I need to save this text to the models that accompany the cells and then put the text back when the cell is used again.
How do I know that the cell is being moved away from? I have other types of cells, so I need a way to invoke some code to do the saving part on the scroll of the UITableView.
I hope that makes sense, if more is required, let me know.
Thanks.
Just save the text once it is changed to the model, check if any text is present and use that in tableView(_:cellForRowAt:)
For more help you will have to show us your code.
You can inherit UITextViewDelegate and in the textViewDidEndEditing(_:) check if the text view is edited, then you will be able to store the text in a variable or somewhere else and restore it whenever you are about to show that cell again.
If there is more than one text view, you might want to set an accessibility identifier for each kind, so you will find out which one did end editing.
Related
I am just thinking. Suppose, i have a tableview which have custom cell. It's simple. But My idea is that, when i click a tableview cell then another tableview is appear under that tableview cell, and again i click that cell then that sub tableview disappear. Similarly when i click second cell than work same. Is it possible? Please Provide me any idea or reference.
This is entirely possible, you're talking about Expandable cells.
My example here
The general idea is that your custom cell has a tableview at the bottom of the cell, and what you do is just change the cell height to display said tableview, on tap.
It's not easy, I'm not gonna lie it took us a while to do it, but we managed, and I'm telling you, it's very possible.
You can find a lot of help using the Expandable Cell keywords.
Note that you're gonna find yourself handling a lot :
What to do when the expanding cells is shown off screen?
What to do when you're expanding the first/last cells ?
What to do when expanding another cell ?
What to do when scrolling inside that cell (a scrollview inside a scrollview !)
There are many cases where it'll work, but won't work fine, and there is gonna be a lot of fine tuning. Specially in our case where we have rounded corners, but only when the cell is expanded, and not in cases where it's the last or first cell (next to section header).
They look cool and make you feel proud, but don't say to your PM it'll be done in a week, because it's a pain to build.
If you want to show additional cell information, you can add more cells after the cell indexpath you have clicked.
Create a custom table view cell classCustomTableViewCell by subclassingUITableViewCell class. And system will generate CustomTableViewCell.h, CustomTableViewCell.m, CustomTableViewCell.xib files for you.
Add protocols UITableViewDataSource and UITableViewDelegate in your CustomTableViewCell.h and implement the required methods in CustomTableViewCell.m files
Add a method for setting datasource and use the datasource for updating the table.
NOTE:
Handle table-dequeue mechanism properly, otherwise you will end up
with weird issues that may take time to investigate and resolve.
If you use this custom cell for all the cells in your parent table then the gestures will only listened by the child table. So plan for that too.
Please visit my blog for the sample code. https://myioslearnings.blogspot.in/2017/03/nested-table-view-in-ios-objective-c.html
I'd like to get every data that is within all cells in one tableview which is quite a long list.
I'm looking for an approach on how to retrieve everything including those hidden in view, which I know the views are reused. I think some of you might have experienced this problem before, what are your approach on this?
I've tried
let cells = self.tableView.visibleCells
then looping into every cell and saving each data to an array but it is not effective in getting those that aren't part of the view or hidden. Is there a way to get over this?
In cellForRowAtIndexPath, YOU are telling the table what is in each cell. So why would you turn around and ask the table what's in each cell? If the user puts "Hello" in your first cell, then scrolls the table enough to push that first cell out of view, then when the user scrolls back to the top, YOU are the one telling it to put "Hello" back in that first cell. YOU own the data source, not the table.
You need a data source. That can be "empty" at first, maybe an array of empty strings if that's what you want (each index in the array could map to a table row for example). But then, as the user interacts with the text fields in the cells, you need to update that data source with the text they entered.
You should use that data source as your source for the cellForRowAtIndex method. That way you can handle populating the cells when they are requested by the table, and you also know all the data when the user is done.
Why not just update the model each time the user taps a key when editing a textfield? You could create a protocol for that cell subclass and make your view controller the delegate for each cell. As long as cells are guaranteed to stay on the screen while you're typing (you'll get some weird behaviors if not) the cell can send a message to the view controller or whatever you hook it up to telling it what new value to store. Then everything is already stored for you when you need the full list, and you don't have to interact with the tableview.
I have another question open where I'm trying to figure out how to reload the collectionView without auto-scrolling. I was also realizing there are a lot of other situations where I will need to change things in the collection view. Also I have some items that I will want to change the .alpha on and change the text of. Is there a way to do all of this in Swift? For example (to be specific) if I have a collection view with a view in each cell and that view has a textField in it, can I change the alpha and text, (change alpha with animation even) without reloading entire table?
Look at the documentation for UICollectionView. There are several "reload" methods:
reloadData()
reloadSections(_:)
reloadItems(at:)
If you just want to reload a single item, update your data source's data and then call reloadItems(at:) passing in the index path for the item.
Another option, if a cell is currently visible, is to use the cellForItem(at:) method to get a reference to an existing cell. Then you can directly access UI components of the cell as needed. You should also update your data model as needed so if the user scrolls and comes back, the cell will be rendered properly.
Most appropriate where you can update your custom view of a particular UIcollectionViewcell is reloadItemsAtIndexPaths.
You would be handling a particular item than whole collectionview with reloadData.
You can handle it via notifications or some call backs in your code where you can make decision when to update which cell.
Hope it will help you.
Our app has a social feed with a name label similar to Facebook with a FeedController and FeedCell class. Each time we scroll back to a previously loaded cell, it reloads, so the name label becomes darker, the text becomes bolder and starts to overlap. How do we fix this? We tried the prepareToReuse method and setting the cell's label to nil, but that did not help. Any help would be greatly appreciated!
It appears that you're regenerating the label and adding it to your cell's content view every time that the label is reused.
Inside your FeedCell class, make sure to only initiate your interface elements in your initializer. From there, you can fill your cell with data in the cellForRowAtIndexPath: method of your UITableViewDataSource.
Inside cellForRowAtIndexPath:, make sure to not add any views to the cell as this could contribute to the issue you're describing. As a rule of thumb, I make sure to initialize the views in the cell subclass's initializer, and only manipulate properties of these views (like hidden, alpha, etc) when working with the cells.
Moving forward, you can use prepareForReuse to clear any data from your cell that may be leftover from the previous time the cell was used. In many cases though, this isn't necessary as the data will be changed in cellForRowAtIndexPath:.
I know this has been asked a lot of times but theres so much different information and different cases, I just don't understand where to begin and cannot get it working in my app.
In my app I have a table view and I'm using a NSFetchedResultsController. In normal mode, the table cells shouldn't be editable but instead each click should be a segue to a new viewcontroller (which works). In edit mode however I want that if you click on the cell, that you edit the text and this gets automatically stored to the database. And here I don't have a clue.
I want it as simple as possible. What I've read so far I guess I have to subclass UITableViewCell and a TextField. Here's already my first question: In each post about this, the TextField is init with a Rect, however how do I know the exact width and height of my cells?
And do I add this cell directly in the cellForRowAtIndexPath? Or only if the mode gets changed to edit? And some posts suggest you have to be the delegate for UITextField, but why?
And is there some sample code for about exact the problem I have? I wasn't able to find it...