This is a stab in the dark that someone would know what is going on here, but i have a UITableView that the user is allowed to reorder. Upon reordering cells I reload the UITableview data (because I change each cells label based upon its order in the table).
[self.tableView reloadData]
However, when i reorder the first cell with any other, everything acts as its supposed to and i get no errors but the first cell disappears. If i reorder any other cells in the tableview everything is fine
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I have a UITableView that contain about 20 rows in the iPad's viewport. I have a interval timer that will call UITableView's reloadData regularly(post it to UI thread).
Now when I scroll through the UITableView with medium speed (not so fast), that UITableView will refresh with flickering effect.
I have to write a function to manually update the UITableViewCell label by looping through all the items in the array (this array keep all the items that show on UITableView). I will execute this function when timer is running instead of calling reloadData (as I mentioned above). Then the flickering issue is gone.
I believe that reloadData should be better than looping through all the data because reloadData will only refresh the current showing Cells instead of all the rows, but I couldn't figure out why the flickering happens. Anyone know why?
One thing I have to mention is I did use the CellIdentifier correctly to reuse the cell and only create the cell when the retrieved cell is null.
Moreover, I do not have this issue in iPhone and I believe that it is because iPhone has lesser row compare to iPad.
Anyone can give some explanation about this issue?
I had the same problem with flickering when using reloadData. I solved it by using indexPathsForVisibleRows and cellForRowAtIndexPath: to only update the visible cells. Performance is good since I don't have to iterate over the whole data set, but only a limited number of visible cells.
reloadData causes the tableview to recreate the visible cells on screen which can result in a flickering since the cells get destroyed. There are better ways to reload the tableview. Are you using Core Data? If so the NSFetchedResultsController and it's delegate are a great way to update a tableview since it listens to changes in the underlying datasource and only updates the appropriate cells.
This problem is driving me nuts.
I have a prototype UITableViewCell in my storyboard. It contains a bunch of subviews. One of the subviews, a UILabel, is misbehaving.
When the tableview loads and is displayed for the first time, all of the cells look fine. However, as the tableview scrolls down, eventually one of the cells shows up without the UILabel subview. It seems that it is always the first cell that is being recycled.
If I continue scrolling down the tableview, however, as soon as the misbehaving cell is clipped by the top of the tableview (when it begins to be scrolled off the top of the screen), the label appears just as it should.
So it seems that the label is there, and it receives the string that I assign to it in my cellForRowAtIndexPath method. It's just not getting drawn for some reason. I've tried inserting setNeedsDisplay messages in various places, but that hasn't helped.
What is also strange is that I'm using the very same UITableViewCell subclass with a duplicate view hierarchy in the storyboard in a different view controller, and there I don't have any trouble.
Anybody have some idea of how I can start to unravel this mystery?
Thanks!
It sounds like it's only a problem when you use a reusable cell, which means that the values on reusable cells may not be getting set until you're ready to scroll off.
I have a tableview with imageviews and textviews in each cell. When my view is loaded one of the textviews is invisible. But when I start scrolling the textview appears, so that my view looks as it is supposed to look. Does anyone know why this is happening?
P.S. I have read about reusing cells when scrolling so I have been very careful to construct my cells correctly.
Without code, no one can give you a exact answer. But for a guess....
Is your data is getting populated after your table call cellForRowAtIndexPath? When the cell populates the first time, no data, so the cell is in it's unformatted state. By the time you can interact with the table and scroll it off and on screen (which calls cellForRowAtIndexPath again), the data has been populated and so the cell looks as expected.
You can test this by putting a breakpoint in your cellForRowAtIndexPath method and check to see if your data objects are initialized or still set to nil.
I have a UITableView and I am having an issue with whenever I try to click on the Cell. When the cell is highlighted it puts some test on top of the text that is already on the cell make the text on the cell hard to read. This only happens while I have the cell highlighted.
Please help me with this issue.
Thanks
I had a similar problem and then realised that I wasn't using the cell dequeuing thing properly and what had happened is that every time the cell is reused a new UIlabel was added and the text from the datasource set to that, but the UILabels from the previous time the cell was showing were still there. But you only see them when the cell is highlighted because when it's not highlighted the background is not clear, but when the cell is highlighted then the UIlabels become clear and you see the other UIlabels that are behind it.
It's quite serious as everytime cell's are dequeued (ie everytime you scroll on the tableview) all of the subviews you've added a duplicated. And it increases memory usage severely.
To fix I used the code from the apple docs on customizing table cells. You have to use tags to retrieve the subviews if the cell is dequeued.:
http://developer.apple.com/iphone/library/documentation/userexperience/conceptual/TableView_iPhone/TableViewCells/TableViewCells.html#//apple_ref/doc/uid/TP40007451-CH7-SW15
I have a UITableView with complex content. The user can edit (rearrange and delete) the cells when tapping the Edit button the standard way. But I want the cells to look different in "edit" mode.
Question:
How to change the UITableView Layout in edit mode, including changing row height?
So far, this is what I have:
The Edit button sends a WillTransitionToState/DidTransitionToState message to each uitableviewcell (UITVC). I have subclassed UITVC and react to these inside each cell, hiding and removing and reshuffling as needed. But, changing the row height is beyond the scope of one cell.
There does not seem to be a message sent to UITableView when user taps edit. There is a - tableView:commitEditingStyle:forRowAtIndexPath: sent to data source after editing a particular row.
Inside heightForRowAtIndexPath, I can query the current mode using the tableView.editing property, and report height as appropriate. And I can trigger re-flowing the table, including recomputing the heights, by invoking [tableView reloadData]. But, when do I call it?
I could send messages from the cells from within WillTransitionToState back to the "owning" table view, and call reloadData when I get them. But this sounds fragile and there must be a better way.
Rhythmic is right. Using reloadData kills the nice editing animation.
This problem is addressed in this post:
Can you animate a height change on a UITableViewCell when selected?
Instead of using reloadData, do the following after calling setEditing:animated.
[tableview setEditing:editing animated:YES];
[tableview beginUpdates];
[tableview endUpdates];
If you wish for your table cells to change their format in response to whether or not the table is in editing mode, you could override -setEditing:animated: in your UITableViewController and trigger a reload (via -reloadData) of the table view on a change of editing state.
Within your UITableViewController's -tableView:cellForRowAtIndexPath: method, you could check for whether or not the table was in the editing state by querying the editing property on the table view, and then return a different cell type depending on which state the table is in.