I have a UITableView in Xamarin iOS and the requirements are this:
There are always at most 10 items to display in a table. There may be less (like 3), but never more than 10.
The Table should always show all 10 rows, and the height should be such that the table never scrolls (because it's only 10 rows).
What would be a good way to make sure it always shows all 10 (or shrinks in height if it's less like 3). This table shares the page with some other elements, so it's not the only thing on the screen. You can scroll on this page.
Right now it's showing the first 5 in the view, but I have to scroll to view the rest. Would this be a matter of me setting the height in StoryBoard to be rather high? But if I do this, would the table shrink automatically if it had a fixed height?
Any advice/recommendations? Again, remember it will only be 10 records, so not a lot to manage in memory. I want to use a UITableView because of the customizations and repetition of the cells, etc.
Thanks!
Related
Vaadin Version: 23.3.3
I have a fairly complex Vaadin table, ~100 rows, each of which contains ~12 columns, each column containing a layout with ~10 elements. The table is not lazy in any way, and is configured to show all rows at once.
It takes the browser 5+ seconds just to render the table after the request is complete (a topic for a different question) but even once the table is rendered I experience some weirdness when scrolling.
When holding the mouse outside the table, or using the scroll bar, the page always scrolls as expected. But when I hold the mouse inside the table I get inconsistent results. If I have first scrolled the page all the way to the bottom then there appears to be no issue regardless of mouse position. But If I have yet to scroll to the bottom, then the table scrolls in place, pushing rows underneath the header (see screenshot). It's as if the browser/vaadin is not yet completely aware of the size of the table?
Is there something I need to be doing to force vaadin to render the entire page?
Edit: Upon some further testing I noticed even stranger inconsistencies. My table cells have two possible layouts depending on user actions. One is simple, containing: div > span > span. The other is more complex, containing a div > span > span + vaadin-icon + tooltip. The issue only appears when the table is rendered with the "simple" layout. Something about the added vaadin-icon and tooltip seems to make vaadin draw the table without scroll issues.
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...
I work on a app, nothing fancy, but since is my first app, there alot of stuff I never did before.
So, I'm trying to build a view like the image attached.
I've looked up on the Internet how to do something like that but I don't know what is better/cleaner way to do.
As you can see I have 3 areas: the title, the tableview in the middle and a button on the lower side.
The table will expand based on the content (3 lines or 30 lines) so the button must move down and a scroll bar should appear.
So, my idea:
Using a tableview having 3 static cells: one to put my title, second to put a tableview having prototypes cells, and a third one for the button.
That way I would have a scroll bar when the table in the middle grows, pushing the button.
Here I have a question: how to have the table view (the inner tableview) resize itself, pushing the height of the middle row, instead of having a fixed width with a scroll.
Is the the best way to achieve that?
Thanks for any idea.
C.C.
Are you sure you want to push the bottom UI down as the table grows? You say whether the table has 3 or 30 cells, but what if it has 300 cells? Your user then has to scroll to the bottom to reach the button and tab bar. I think you'll find that it would be better to use Auto Layout and let the table fill the screen space between the title and the button. The table will scroll so if you have 300 cells then you can scroll through inside the table's available area.
The advantage here is you won't be fighting with Auto Layout. If your user rotates an iPhone 4S into landscape you'll only have a few rows displayed but conversely if they run in portrait on an iPad you'll fill all of that space.
As for how to do it, the other advantage is that you don't need the nested table you describe. Use a constraint to attach the title label to the top layout guide, then attach the tab bar to the bottom layout guide. Put a vertical space constraint between the button and the tab bar. Finally, put vertical space constraints between the table and the title & the table and the button. (You'll need to implement constraints for the horizontal axis as well, but that's pretty simple.)
There's are refinements you can put into place if you want the table to shrink to fit if there are only 3 rows, but this should get you started and you may not want that anyway.
Key point: the tableView wants to scroll naturally, inside a view sized to fit the display. Don't change that behavior unless you really have to. Neither your users nor UIKit expects what you're trying to do, and the table is going to fight you all the way about it.
Nesting UIScrollViews (which your nested table would do) works, but it opens up a lot of bad UI flow problems. In my experience every time somebody wants nested scrollViews there's some other approach which is more "natural" to iOS interface paradigms.
If you're dead set on the UI you described I wouldn't use a table for the outer structure. Just make it a UIScrollView and calculate your content size based on the number of rows the table will display. You can actually do that, and then use Auto Layout as I described.
I have an iPad app which always stays in landscape mode. It is more of a data centered app with 5 columns and couple of hundreds of rows.
In current implementation, I have used UITableView. The rows' height could be anything depending on the data that comes in from server and all the columns can have different size.
The question is, can I use UICollectionView instead of UITableView? Will there be any performance issues? If yes, which is better in grid like layout? I understand UICollectionView is to be used in iOS pictures app like layout but how it behaves for grid like layout?
Thanks,
Pruthvid
What you describe is exactly what UICollectionView is designed for, it's the perfect solution. The limitation is only to the version of iOS you will be able to support (if you need to go back that far).
The choice really comes down to the visuals you want. Of you want each row to have a height defined by the maximum height of any column value in that row and the row appears as a single row item and the last row of the table should be full width then you may prefer to use a table view.
The collection view gives you more options for accessory views (as opposed to just the headers and footers of the table view).
(please forgive my english)
I'm new at IOS developing but I've a good skill on other programming languages (mainly c#).
I'm trying to develop a test app with a main window.
Inside that window there is a scrollview with fixed size. inside that scrollviewer there is a view containing some stacked couples of one TextField and one Label: I can't know - ad design time - how many "rows" of them I have to put into.
My problems is:
I can put on the view the first couple (a textfield and, next, a label). Label size can be one or several rows high ,so I've to set multiline and sizeToFit
How can I put the second couple (and so on) without overlap the existing labels..? I can't use a table because between rows there are other labels (title of section).
Do I have to calculate the height of each label and programmatically calculate where to draw the next? Is there a more efficient way?
I don't need code, please just some hints or some keyword to googling on.
Many thanks.
I don't see why you can't use a UITableView, you can set up cells with all the controls you need in it. Either way, using a UITableview won't make the job any easier (just more memory efficient if you have many rows).
The only way that I see is, as you said, to calculate where the next 'row' should be placed (depending on the height of your previous rows). You'll also need to calculate the entire height, in order to set it to the contentSize of the UIScrollView.
Instead of UILabel you can also use a non editable UITextView, since it'll be easier to get its size (after you set the text, you can set the size of a UITextView to be equal to its contentSize)