I have a horizontal-scrolling UICollectionView which is nested in a UIView that is centred and occupies 80% of the screen width.
I want the UICollectionView to be visible screen edge-to-edge rather than constrained to the super UIView bounds.
I have set the following which shows the UICollectionView across the screen width:
collectionView.clipToBounds = NO
...but when dragging the collectionView, it hides cells when they are completely outside of the super UIView bounds even though they are partially visible on the screen, which leads to a weird flickering of blank space/cell.
Ideally, I'd like a way to prevent the hiding of the cells completely out of bounds. Is there a way to do this?
The UICollectionView has a maximum size of 3 cells, so I'm not particularly worried about any performance implications of having all cells visible all the time.
The only way I found is to enlarge the frame of the collection view (and its superview in your case) and add contentInset's to it. You might also want to update scrollIndicatorInsets.
Related
I have the following autolayout-driven setup:
Main viewController, with a scrollview inside it. Scrollview pinned to superview edges. This one scrolls up and down.
A few normal, fixed size views at the top of the scrollview
Another scrollview. This one scrolls left and right. The second scrollview contains a couple of tableviews, side by side. The idea is that the user can switch between them. They both contain a handful of cells, all the same width as the screen and 72pts tall.
The problem I'm trying to solve is that the tableview contents are not the same size. The left one has say, 6 cells, and the right one has 3.
My first approach was to dynamically change the second scrollview height to match which ever tableview was currently visible. What ended up happening was that switching between the two tableviews (by doing setContentOffset:animated:) went extremely wrong if animated was set to true - it would adjust the content offset so everything was offscreen. In fact it would set the content offset to and then as I switched, about a dozen times, then it'd reset. It was weird, I gave up.
Now I'm trying to just adjust the content inset of the main scrollview to offset the gap in the content of the current tableview, and it's also being weird. When I set the bottom content inset in viewDidLoad, it works fine. When I set it at the time the tableview becomes current, it does nothing.
What gives? What scenarios would lead to these view interactions not behaving properly?
Use different tableViewController for each table.
Embed them in pageViewController.
Add those few normal, fixed size views at the top of the pageViewControllers view.
Conform scrollViewDelegate in pageViewController.
Pass scrollViewDidScroll from tableViews to pageViewController.
Set tableViews inset to match those fixed size views at top.
Change height according to the scroll.
This is the way you can achieve the functionality you want.
I hope it helps.
I have a UITableView at the bottom of the screen that pulls up and then snaps back down. When it is pulled up, though, you can see the view behind it because the tableview's height is finite and less than the size of the screen.
I tried using a large footer, but that affects the snap-back of scrolling the table up.
I also tried setting a fixed height for heightForFooter and returning a large view from viewForFooterInSection, but that view gets cut off after it reaches the height returned by heightForFooter
How can I display fixed content beneath my table without affecting its scrolling?
Add a background view to your table view, and then add a subview to that view with the color you need. You can position the subview around table/section headers.
In viewDidScroll, update the y position and height of the subview.
I have a UIScrollView designed with IB.
UIView
UIScrollView
UIView
UITextField
UIButton
...
If I tap on the text field the view scrolls away towards the upper left corner of the screen before the keyboard is appearing. The space above the keyboards remains empty. I can scroll back the view if I drag in this empty space.
I have googled around, but found only postings where users want to scroll UIScrollView. I want the view to stay where it is.
Thanks in advance for any suggestions.
Here's what happened.
You designed the whole thing in Interface Builder.
The scroll view was not scrolling, so you set its contentSize in code to the size of the scroll view's primary subview (what I like to call the content view).
The scroll view was still not scrolling, so you munged the content insets - and this caused the problem that brought you here.
Your mistake was (3). Instead, you should have thought more about (2), i.e., why isn't my scroll view scrolling even though I have given it a nice big content size?
The answer is that, in a storyboard or xib that has auto layout turned on, that's not what you do. What you do is use constraints from the content view to its superview (the scroll view), on all four sides. Set the constant for all four constraints to zero. This causes the content size to match the size of the content view, automatically.
I have an UITableView that does not fill the whole screen, so there is some space at the top and the bottom of the screen. This table uses table.clipToBounds = NO and table.bounces = YES.
But when scrolling the cells outside the original frame of the table, the cells are hidden. I know that's the normal behavior of UITableView to increase performance. But is it possible to define an area at the top/bottom of UITableView within which the cells are not hidden? Or even set a cell property to be "always" visible?
Subviews outside bounds of superview are hidden (table view's cells are also its subviews). That's just how iOS view hierarchy works, not really about performance. And it doesn't make any sense when a subview/cell is displayed on the screen while user cannot interact with it (because it's out of bounds). In particular, table view reuses cells that go out of its bounds, so no, you cannot set a cell to be "always visible".
I've created a UITableVIew and it is a subview of a UIView. There are three issues that i'm having and it is only occurring on iOS 4 devices:
1) The table doesn't bounce when the view hits either the top or bottom of the table while scrolling. The vertical bar doesn't shrink either, it feels sticky and it is very much acting like an Android table view. I've tried enabling the bounce property but that doesn't make any difference.
2) The horizontal scroll bar appears when the view is scrolled down to the bottom of the table. This shouldn't appear since the table view's contentSize has been set correctly. It does eventually disappear when the contentSize is set 20 pixels less than what it should be.
3) I can't scroll to the bottom of the footer view, and only half the footer view is visible.
I've added a UITableView as a subview to other views throughout my project and this has never occurred, and so i've copied the way that I create other UITableViews, but still no luck.
Any suggestions would be greatly appreciated.
Thanks,
Ankur
I worked out the problem. The problem is a little strange, although i had a feeling that the way i was coding was a little messy.
I am subclassing a View, and the parent view has a layoutSubview method, which is only calculating and setting the frame for a table view subview. In the subclass, i had to override layoutSubview for the same reason as the values for the table view's frame need to be different. This means that the table view's frame was being laid out twice, once by the parent class and a second time by the subclass. It seems that iOS 4 doesn't like this, and i should only set the frame once per subview per layoutSubview call.
Now i've created a layoutTableView method, which is called from the parents layoutSubview, and i've overridden layoutTableView in the subclass. Therefore the table view's frame is only being set once.