I am facing a strange issue with UITableView if I enable the UITableViewAutomaticDimension property.
I am fetchign some data from the server and I have kept my UITableView cell set to accept dynamic content and increase the height as per the content so far what i have done is
Set the number of lines of the UILabel to zero so that it grows as per the content
Added the below code inside the viewDidLoad method
self.myTable.estimatedRowHeight = 200
self.myTable.rowHeight = UITableViewAutomaticDimension
Now after i fetch the data from the server i reload the table and go to the last cell of the table view but my problem is when i reload my entire table after the webservice call,
the table view animates and scrolls to the top of the screen and is not visible unless I scroll it down.
I searched and googled but i was not able to find any solution to this but if any of you have every came across this kind of situation please guide me out.
I have even added the below line of code before returning the cell in the cellForRowAtIndexPath but still am stuck with the same issue
cell.layoutSubviews()
here's the code which i have added to scroll to the bottom cell after the successful service call
self.myTable.scrollToRowAtIndexPath(NSIndexPath(forRow: self.myArray.count - 1, inSection: 1), atScrollPosition: UITableViewScrollPosition.Bottom, animated: true)
Related
I know there are tons of questions about tableViewCell disappearing on scroll, but none of those fit into my situation.
I say disappear, I mean the whole cell disappears, not some of its subviews.
Here's my situation:
I have a tableView with custom cells, each one of them is very complex, some could even host up to three collectionViews in them. Most of these cells are only displayed once, so I cache them. I retrieve data from network, and use it to populate the cells. As sometimes the data may not be fully available, some sections of the cell needs to be hidden: the cell will set some of its collectionViews' height constraint to zero, and isHidden to true, then notify the tableView, who will reload the cells' heights using:
tableView.beginUpdate()
tableView.endUpdate()
I have noticed two behaviors:
1:
If none of the cell's portion is hidden, the cell works perfectly, except when I scroll(from bottom up) too fast, the cell disappears before going out of the bound of the tableView. When I scroll slow, this does not happen.
2:
If some part of the cell is hidden, the cell will disappear before going out of tableView EVEN WHEN I scroll very slowly.
Sorry I cannot post any code, but what I might have done wrong?
P.S.: In my tableView's row height delegate method, I have:
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return cellHeights[indexPath.row] ?? 0.1
}
cellHeights is where I use a dictionary to store computed height of the corresponding cell. I am certain that these height values are correct, because when I scroll from top down, the cell looks all right. This only happens when I scroll from bottom up.
I did some experiment with the default height 0.1. When I changed it to 1000, the cells are disappearing randomly even more. 0.1 looks relatively stable, but the problems above still exist.
Thanks.
I'm struggling with wired kind of problem. I have UITableView with one cell. This cell is only holding containerView with childViewController (second tableView). My problem is that, first tableView(parent) must have UITableViewAutomaticDimension row height but it doesn't work (It dosen't know correct size of that cell with second tableView).
How to get correct size of second tableView) ?
Second tableView (inside Cell) have scrollingEnabled turned off (tableView.scrollEnabled = false), first tableView must have correct size of second tableView in order to provide correct scrolling experience.
Since a UITableView inherits from UIScrollView you can use the contentSize property to get this information. This is how the scrollbar works on the side.
I have done a similar thing before (long ago), so the following is somewhat hazy/ irrelevant/ unessecary. There might be some gotchas with unknown/unrendered cell heights in the embedded tableview. I rememeber having to set the tableview height to a large number (forcing all cells to render) fetching the contentSize then resetting the tableview height to the contentSize.height.
Are you shure you really need second table view? If you have just one cell probably you don't need it. I recommend you to calculate table view height as the summ of it's cells heights. If cells of embedded table view have constant height it could be simple. In other case you also could calculate cells height.
In my code, I've overridden tableView:willDisplayCell, and when the last row is shown, I start a load for more data. When this data comes in, I call insertRowsAtIndexPaths to add the rows.
This generally works (the tableview's scroll position doesn't change), but I've noticed that if I overscroll and not let go (scroll past the end of the tableview) that the tableview will jump to the top when insertRowsAtIndexPaths is called upon data load.
I'm using UITableViewAutomaticDimension/Autolayout for my cell heights, as each cell has different heights depending on the data they contain. How can I avoid this issue? Ideally if the data loads and the tableview is over scrolled, the scroll position would stay at the overscroll once the data comes in.
You can create a reference on the bottom cell indexpath, and in whichever function is causing it to go back to the top, call
[self.tableView scrollToRowAtIndexPath:path atScrollPosition:UITableViewScrollPositionNone animated:YES];
SWIFT 3
self.tableView.scrollToRow(at: indexPath, at: UITableViewScrollPosition.none, animated: true)
Summary
Resizing and reloading rows in a tableView where every cell has a dynamic height calculated by constraints causes a lot of other cells to recalculate unnecessarily. How should I solve this?
An example project can be found here.
Long version
I have a view that shows the details of a company and a variable amount of cells (or cards) with more detailed information. I implemented this in a UITableViewController with dynamically sized cells, using auto layout constraints (mostly helped along by this Ray Wenderlich tutorial).
The view has the following cells with variable heights:
Section 0
Row 0: Header image
Row 1: Company information
Row 2: Buttons
Section X > 0
Row 0: About Card
The 'About Card' may or may not have a header image and can be expanded to show the entire text.
Currently I'm having four problems with this:
The UITableViewController is pushed with animating: true. However, the tableView starts out behind the navigation bar and jumps down when it's finished animating. No clue why.
Update This doesn't appear to happen consistently. Joy.
When doing an action that should reload the buttons to indicate the state change, it reloads the button cell nicely. However, it also causes the company info cell to jump down and animate upwards.
Updating the cell happens with the following code:
func organizationRequestsUpdated() {
self.tableView.reloadSections(NSIndexSet(index: 0), withRowAnimation: UITableViewRowAnimation.None)
}
Tapping an About Card should expand it. I'm currently achieving this by setting label.numberOfLines = 5 at the cell initiation and using this for toggling the expand cards:
#IBAction func tapped(sender: UITapGestureRecognizer)
{
if let view = sender.view?.superview as? OrganizationDetailAboutCardCell {
tableView.beginUpdates()
view.toggleReadMore()
tableView.endUpdates()
}
}
func toggleReadMore() {
let expanded = aboutTextLabel.numberOfLines == 5
aboutTextLabel.numberOfLines = expanded ? 5 : 0
}
I'm pretty sure all of these problems have to do with the automatic sizing of the cells with the constraints. However, I'm currently at a loss on how to fix it. Has anyone done automatic sizing of cells with constraints and updated the cell heights without all the tableView doing weird jumps?
Popping back to the UITableViewController has most of the cells at the wrong heights. No clue why.
Things I've tried
Problem 2
For problem number 2, I've already tried updating reloading only the button cell;
self.tableView.reloadRowsAtIndexPaths([NSIndexPath(forRow: 2, inSection: 0)], withRowAnimation: UITableViewRowAnimation.None)
However, this counterintuitively caused all the cells in the section to recalculate incorrectly, ending up with a heap of too small cells. I've also tried this UITableViewRowAnimation.Fade however, this had the same result.
Have you specified an estimated row height? I found this to be the source of many of my layout issues when I did this.
Another possible problem is that you need to assign fonts to labels to make them layout properly. So in your cellForRowAtIndexPath methods, specify the font that should be used on all labels/textfields/textviews.
Here is an example project here: https://github.com/sgoodwin/SelfSizingCells.
Good luck!
I am having a tableview in which I am displaying my data. As you can assume from the title, these cells are dynamic in their content, and so should their height be. Actually I got it working, but I have a strange issue with the row 0 and 7. These 2 rows take my entire screen, but when I scroll past them and go back again everything is fine. I am not sure but the 7. cell must be among the first cells that are being "dequed" when I scroll down. But as I said, this is just the first time they are being displayed, when I scroll again to one of them, everything is looking good (when filling the tableview with new data it is also fine).
I tried to reload the tableview twice when it is being populated for the first time, but without success. The presentation of the first cell I have fixed calling : self.tableView reloadAtIndexPaths ... when the table is being populated for the first time,
and it worked, it has the height it should have regarding its size. But I still have the issue with cell number 7 (the above fix does not work for this cell, I assume because it is not being displayed at that moment)
I am not using any fancy height calulation, just the iOS 8 feature:
self.tableView.rowHeight = UITableViewAutomaticDimension
self.tableView.estimatedRowHeight = 80
Is there a method, fix with which i can force the tableview to draw the cells again ?
Thanks
Cell size is calculated from constrains. So I assume there is something wrong with those or with data during computation.
try this:
in tableview cell subclass use -prepareForReuse method to clean cell data as before reuse.