I'm using a nav bar orchestrated set of tableviewcontrollers to display a hierarchy of data. The bottom level of data is displayed in a custom tableviewcell, which has its content described in a xib, and results in a required cell height larger than the default. I posted another question on how to programmatically extract the resulting cell height, but no usable answers, so I now implement heightForRowAtIndexpath to return a hardcoded value that is the height in the xib attributes panel. But, when the table is displayed with more rows than can fit in the normal display size (480h,320w), the bottom row is chopped off as expected, but I can't scroll it to see the rest of the row. I've searched rather extensively, but nothing has helped. I poked at various attributes (tableview sizes, scrollingEnabled, etc.) but they all seem as expected values (e.g., scrollingEnabled is true). One post suggested that no scrolling would occur unless the contentSize was larger then the frame, so I looked at those values, and it sounds promising, in that my frame size is a typical 460h x 320w, but, my contentSize is 0 x 0! Further searching (e.g., "setting contentSize" or "contentSize is 0") didn't clear anything up. I thought contentSize was computed for free from the table row count and their heights, so how could I be getting 0? Even going back to allowing a default row height by not implementing heightForRowAtIndexpath still resulted in a 0 contentSize. Some searches suggest turning off autoLayout for the custom table cell, but still the same. So, what might be going awry? Thanks for any thoughts or guidance.
Update: Sorry, I confess! I had originally been developing on a mac mini with a regular USB mouse, where scrolling in the simulator was left button down and drag. I recently switched to an iMac with the magic mouse. I'm now so used to just dragging my finger on the mouse to scroll code, web pages, etc., that I didn't think to try clicking and holding the left mouse "button", and then dragging the mouse. When I did, everything worked as expected. I had really thought things were hopeless when any similar variables/values in the app on the mini were equal to those on the iMac, but it was just me getting tricked by fancy technology. Sorry for the distraction.
set your tableView's frame and your cell's frame correct,and implement
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath in your UITableView to give a right height. If that doesn't work try set your tableView.autoresizingMask to UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight;
which can help you with the size of the tableview
I had a similar problem. My tableView would't scroll when the content exceeded the tableViews frame.
The problem for me was that I had "Use Autolayout" checked but no constrains on the tableView. Adding vertical and horizontal space constrains on the tableView fixed my problem
Related
Nowadays fortunately it's trivial to have an iOS table where every cell has a dynamic height. So in the cell vertical constraints ..
---- top of content view
- vertical constraint to
-- UILabel, with, .lines set to zero
- vertical constraint to
---- bottom of content view
Assume the UILabel texts vary greatly one word, 20 words, 100 words,
In the table set
tableView.rowHeight = UITableView.automaticDimension
tableView.estimatedRowHeight = 200 // say
and you're done, these days it works perfectly of course.
However, I had the common situation where you load the table, imagine ten cells.
I populate the UILabel with "Loading..."
Only then - say, a second or two later - do we get the information for the text content. It arrives say a second later and the cell changes the text to "Some long text .. with many lines".
In fact I was surprised to learn it seems UITableView does NOT handle this. The cell in question gets stuck on the original short height.
So, after the larger text is set, I tried all permutations of the usual:
maintext.sizeToFit()
contentView.layoutSubviews()
contentView.layoutIfNeeded()
on the cell, doesn't work.
I tried sending a setNeedsLayout and/or layoutIfNeeded to the table itself, doesn't work.
I thought about .reloadData() on the table itself but - doh - that would again trigger the content being drawn from the server and loaded again, so that's not ideal.
Please note that:
Obviously there are any number of workarounds for the specific example such as not using dynamic data
I am completely aware how to manually animate the height of one cell (like when you "expand" one to show something else when the user taps)
This question is about autolayout and table view - which, thanks Apple, nowadays flawlessly handles completely dynamic cell heights involving UILabels with lines zero.
But what about if the text in such a label changes?
It seems that the table view system does NOT handle this.
Surely there's a way?
When the content of a cell changes the layout (in this case, the height) you must inform the table view that the layout has changed.
This is commonly done with either:
tableView.beginUpdates()
tableView.endUpdates()
or:
tableView.performBatchUpdates(_:completion:)
Why is that not triggered automatically?
I suppose it could be to allow you to do your own animation, or you may want to delay the update, or some other reason that doesn't come to mind at the moment.
Or, it may be due to maintaining backward compatibility?
I don't know. I imagine Apple could tell us...
on the iPhone 5s it seems as though the last item of a specific list shown using UITableView goes slightly off screen and unable to select. Is their any simple way to prevent the tableview from displaying contents offscreen besides checking overtime data is reloaded and the current height of the view?
EDIT: This is all done programmatically and all other tableviews display correctly on the 5s I have tried fiddling with constraints but could not see a difference.
It sounds like your issue has to do with constraints. I'm not sure whether you're using a storyboard to build the view or not, but probably what you need to do is constrain the table view to the bottom of its superview.
I have a UITableView with Custom UITableViewCell's. The Cell's can vary between 200.0 and 300.0 and height.
Now if you open Facebook, you'll notice the scrolling in the News Feed is awfully choppy. However, this is likely due to that various videos that are loaded on every cell, and that the time taken in cellForRowAtIndexPath is greater than 13.67ms (1s/60frames). Hence the choppy 'flicker'.
Quora on the other hand has cells that are varying heights, between probably 150.0 and 400.0+. It scrolls pretty smoothly however.
Now, when I scroll my tableView it's as though my screen is 'jumping'. I will scroll down, and every now and then (may every new cell dequeue but not quite), it's as if something higher up in the tableview got a few pixels shorter in height, and therefore the screen i'm currently viewing jumped up a few pixels. (This is not what's happening, I'm just trying to paint a picture of what it looks like).
Now I know it's not a time related issue. My cellForRowAtIndexMethod is nowhere near 13.67ms. It's always around 3ms, so that's not the issue.
2 questions...
1) Is this typically indicative of an auto layout issue?
2) Is there an accurate/semi-accurate way to calculate estiamtedRowHeight when you have such varied cell heights, or would having an accurate number here not fix this issue anyway? Just an idea.
I'm trying to use Auto Layout for a custom Table View Cell in my app.
I can't seem to get the constraints quite right.
I layed the labels out in the custom Table View Cell, but the labels are still getting cut off. Any ideas?
Thanks! Will post anything else needed. Tried to show needed info in picture below:
Debugging in Xcode. Somehow what shows in Simulator looks different than in Xcode debug.
Here's the width of my TableView shown:
UPDATE:
The problem here was related to what user matt said in the accepted answer, but I wanted to make the Q&A a bit clearer now that I have it figured out for anyone else that comes across this.
In his initial comment, he mentioned the Xcode View debugging, which was great and I was able to dig into a little bit more. Its called the Assistant Editor: Device Preview, where you are able to see the layout and layers of what is onscreen to see if maybe you have labels overlapping or going offscreen based on the device it is running on. If you want to check multiple device sized, just hit the plus icon in the lower left hand corner of this picture.
This helped me find overlapping layers and sizing issues with the TableView. I was able to see how it looked on each device size.
What also helps here sometimes to use the Pin menu. Sometimes the labels can run off screen because it doesn't know where the constraints of the cell are based on the device size. So your label can run offscreen if the label is based off of a landscape layout but the device is an iPhone 5 and is in Portrait for example. This is the Pin menu:
Hope that makes sense and gives some more color to the problem. Let me know if you have any questions at all, thanks for the help everyone!
The problem is that you are using auto layout but you have not done anything about sizing the table view. The table view here is not your view controller's view; it is a subview. Your view controller's view is automatically sized to the size of the device / window, but its subviews are not automatically resized. So you are ending up with the table view much too wide for the device; the whole table is sticking off into space on the right side.
Use a trailing space from the right side of your labels to the edge of their superview, and set it to greater than instead of equals with a value of ~ 5
Review the constraints of your tableview with the View. Draw cell border, label border and tableview border with different colors to know which elements do not display correctly.
Ex:
#import <QuartzCore/QuartzCore.h>
...
cell.layer.border.width = 1;
cell.layer.border.color = [UIColor blackColor].CGColor;
The thing that worked for me to solve views being clipped was to uncheck "Constrain to margins" in Auto Layout.
We have a UITableView that we have configured to act like a Grid, allowing both horizontal and vertical scrolling. We accomplish this by dynamically changing the ContentSize in a custom UITableView's LayoutSubviews method, which helps with autorotation, scrolling, etc.
Everything works as expected except on a couple of our larger grids. When these grids are scrolled horizontally (swipe left), as soon as the ContentOffset.X is greater than or equal to the Bounds.Width, the table view disappears. It is still present and receives input, but nothing is painted. On swiping back to the right, as soon as the width threshold is crossed, everything is repainted.
In situations where the size of the grid is less than half of the configured UITableView width, this issue does not occur. We cannot change the size of the grids because they are configured by customers in the field who expect the data to be available.
I have checked and/or removed as much of our custom drawing code as possible and the issue is still occurring. Does anyone have any ideas?
That is because although the UITableView inherits from the UIScrollView, it is only meant to have a single column, hence it draws its cells according to its Bounds.
If you want to create a grid-like control with the UITableView, I suggest using multiple table views in a parent UIScrollView side-byside and change that one's ContentSize.
I came across this same issue and posted a bug report (10561166) back in December on the Apple Developer site.
I received a response today from Apple in which they stated that
UITableView is not designed or intended for horizontal scrolling.
(I had since changed my design not to require the horizontal scrolling.)