I have a UIView in which I am adding a UICollectionView to act as a banner view to look like a carousel. The Viewcontroller in which UIView is present, is part of pageviewcontroller.
PageVC --> UIViewController --> UIView --> UICollectionView.
Each VC has its own banner, so when the page is swiped, I reload the collectionView with the respective data and I am able to see it. Now if visit a page which I already visited, the collectionview cell disappears. The collectionview is visible but the cell is somehow hidden.
The collectionview cell is a customcell and I am not using any custom layout, I am using the default flowlayout. This is working fine in iOS8-devices.
Below is the debugger output,
When cell is visible:
CollectionViewCell: 0x7f9db8d9ffa0; baseClass = UICollectionViewCell; frame = (209 3.5; 209 96); clipsToBounds = YES; opaque = NO; layer = <CALayer: 0x7f9dbb5dde60>>
When invisible (you can see its hidden now) the dequed cell is now hidden, no clue why it is happening
CollectionViewCell: 0x7f9dbb5897e0; baseClass = UICollectionViewCell; frame = (0 3.5; 209 96); clipsToBounds = YES; hidden = YES; opaque = NO; layer = <CALayer: 0x7f9dbb590220>>
indexPathsForVisibleItems is returning nil.
I was calling reloadData from multiple places which caused the system to get confused (may be) especially I have written reloadData in my updateconstraints method and hence for each minor constraint change reloadData was getting called.
Check all places from where you call reloadData for collectionview if you're experiencing the same problem.
I've encountered the same problem.
After
checking if the UICollectionView reloadData was called in some thread other than the MainThread
checking if there is any cases about multi-calling reloadData or updateconstraints
without solving my problem, I realized that in some occasions CGSizeZero was returned for collectionView:layout:sizeForItemAtIndexPath:.
When avoiding the CGSizeZero result, everything works well.
Same problem.
Here's my situation:
My collection view has a custom layout. I use the default flow layout without any problem.
When I use my custom layout, whose cell width is a half screen width. When I scroll to the 5th cell, all cells became hidden without reason.
Finally I found out that when I set cell's size correctly in the layout class of the storyboard, the problem is resolved.
Hope this helps.
Related
I've created a UITableViewController in my storyboard, and added a UIView as a tableHeaderView. I have an MKMapView in the tableHeaderView, but my problem is that the map in the tableHeaderView doesn't receive touches before the tableView completely stops scrolling. Rather if a touch occurs before the scroll ends decelerating, the scroll continues, and this is unwanted behaviour.
I've already tried subclassing the UITableView to override hitTest, but can't figure out what to return as the output of events within the tableHeaderView are as follows:
<MKNewAnnotationContainerView: 0x1589ac3a0; frame = (0 0; 375 310.5); autoresize = W+H; autoresizesSubviews = NO; layer = <CALayer: 0x170c3c5e0>>
So, is there a way to interact with the tableHeaderView simultaneously when the scrollView is decelerating?
It seems TableHeaderViews are not really made for things like this. You should simply add the MKMapView at the top of the UITableView, this will solve your problem.
An UISplitViewContller's the master view controller (TAbleView) has 2 types of cell prototypes.The iOS's default one is working fine but my custom cell has layout problems so all the subviews are missing.
If I present the master view controller modally all the subviews in the cell are laid out correctly.That means it is not related with the constraints set inside the content view of the cell.
Is there something special that i need to care about?
Second cell's subview are missing.
How they should look like.
Edit:
If i debug the layoutSubviews, i see that coordinates of the labels are not right.
<UILabel: 0x7fa8f0de82f0; frame = (0 -21; 42 21); text = 'Subtitle';
opaque = NO; autoresize = RM+BM;
userInteractionEnabled = NO; layer = <_UILabelLayer: 0x7fa8f0de84a0>>
Constraints for the Subtitle Label
After playing around with constraints I figured out that the problem was related with the size classes.
You need to specify the constraints for Splitview's master in ANYxANY size class not anything else.Mine were added in Regular to Any.
There were auto-resizable table view cells introduced in iOS8 (WWDC Session 226 What's new in table and collection views).
In my project I'm trying to implement old fixed rows height behavior. Also, the most important thing for me is to inset default cell.contentView frame with margins on the left and right side.
So, I change the cell.contentView.frame property and immediately after that the -[cell setNeedsLayout] method is being called and and it leads to cell get stuck in an infinite layoutSubviews loop.
Steps to reproduce:
Create new single view project and replace default view controller with the table view controller
Disable table view automatic height calculation
-(void)viewDidLoad {
[super viewDidLoad];
self.tableView.estimatedRowHeight = 0;
self.tableView.rowHeight = 44;
}
3. Drop a custom cell in the table view in storyboard,
Add any subview to the custom cell:,
Subclass the cell and change contentView.frame in layoutSubviews,
Build and run.
Result:
Simulator ends up in a black screen stuck in a infinite layout subviews loop.
Expected Result:
Simulator displaying a table view with a cell's contentView having a custom frame.
Comment:
While debugging a little bit, I found that the infinite loop can be avoided if the cell does not have any custom subviews dropped on it. So it seems the bug will appear after the following conditions are met:
self.tableView.estimatedRowHeight = 0; self.tableView.rowHeight = 44;
cell.contentView.frame = CGRectMake(...)
cell have custom subviews dropped on it in xib or storyboard
Apple does not have the issue in the "Known issues" list for iOS8, so I'm wondering is it actually a bug in iOS8 or does anybody know how to resolve the issue?
This is not a bug: setNeedsLayout will be called any time you change view's frame.
My guess is that changing cell.contentView.frame also changes cell.bounds in iOS 8, triggering relayout. This behavior may be different between iOS versions; anyway, those are standard views, so we shouldn't change them in unsupported ways.
Rather than operating on cell.contentView, how about adding a custom view with insets to it? Or simply creating a height constraint?
In ViewDidLoad please use the below line and there is no need to give the row height
-(void)viewDidLoad {
[super viewDidLoad];
self.tableView.estimatedRowHeight = 44.0f;
self.tableView.rowHeight = UITableViewAutomaticDimension;
}
My UICollectionView cells don't get displayed on iOS6, because my delegate method cellForItemAtIndexPath doesn't get called. I suspect because of this warning:
the behavior of the UICollectionViewFlowLayout is not defined because:
the item height must be less that the height of the `UICollectionView`
minus the section inset's top and bottom values.
I don't get the warning on iOS7, and all the cells display correctly there too.
I've set my collectionView frame to height 270 in the .xib and there are no insets defined.
I've set my cell height to 270 in the .xib.
I can print out my collectionView frame at runtime and it's 271.
Also, my collectionview is actually inside a custom tableview cell.
Any ideas?
Thanks!
Try to set self.automaticallyAdjustsScrollViewInsets = NO
This was introduced in ios7 so you might want to wrap that with an ios version check, if you are supporting ios6 and below.
This fixed my problem! In my .xib, setting my Collection View Size Cell Size to a smaller value.
My setup is that I have this collectionview inside a custom tableview cell and
I do return the height of my tableview cell programatically (depending on the content). So it could be that my warnings had to do with my collectionview not fitting inside the tableview cell. So setting the initial collectionview to a smaller value fixed it.
I was on the wrong path thinking that the problem was with my collectionview and its colletionview cell.
Maybe?
self.automaticallyAdjustsScrollViewInsets = NO
actually did the trick. it also resolved my issue in swift, where the cells of a horizontal flow layout had a frame top of -32 (???) and did not fit into the collection view properly.
I found that I had to manually set self.collectionView.collectionViewLayout.itemSize in viewWillLayoutSubviews.
- (void)viewWillLayoutSubviews {
self.collectionView.collectionViewLayout.itemSize = CGRectMake(...);
}
Another possibility to generate the same trick would be to implement the method
collectionView:layout:sizeForItemAtIndexPath:
I have the same issue, in my case the size of collectionCell in storyboard is 96x96 and also under -(CGSize)collectionView:layout:sizeForItemAtIndexPath:
the solution was removing this delegate:
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
UIEdgeInsets insets = {.left = 10, .right = 10, .top = 5, .bottom = 5};
return insets;
}
And by the way this is under ios7, it's late but hope this will help some.. Cheers..
Set:
self.itemSize = CGSizeMake(1, 1);
I have a grouped tableView in my iPad-app, and I've been trying to set cell.imageView.center = cell.center to center the image instead of putting it to the leftmost position. This is apparently not possible without a subclass of the UITableviewCell(If someone could explain why, that'd also be appreciated.. For now I just assume they are 'private' variables as a Java-developer would call them).
So, I created a custom tableViewCell, but I only want to use this cell in ONE of the rows in this tableView. So in cellForRowAtIndexPath I basically write
cell = [[UITableViewCell alloc]initWith//blahblah
if(indexPath.row == 0)
cell = [[CustomCell alloc]initWith//blahblah
This is of course not exactly what I'm writing, but that's the idea of it.
Now, when I do this, it works, but the first cell in this GROUPED tableView turns out wider than the rest of them without me doing anything in the custom cell. The customCell class hasn't been altered yet. It still has rounded corners though, so it seems it knows it's a grouped tableView.
Also, I've been struggling with programmatically getting the size of a cell, in cellForRowAtIndexPath, I've tried logging out cell.frame.size.width and cell.contentView.frame.size.width, both of them returning 320, when I know they are a lot wider.. Like, all the rows are about 400 wide, and the first cell is 420 or something. It still writes out 320 for all the cells..
This code will not work for a couple of reasons:
cell.imageView.center = cell.center;
Firstly, the center is relative to its superview. I believe the cells superview is the tableView. The imageView's superview will be the content view of the cell. Therefore the coordinate systems are different so the centens will be offset. E.g. the 3rd cell down will have a center of 0.5 widths + 3.5 heights. You should be able to ge around this issue by doing:
cell.imageView.center = CGPointMake( width / 2 , height / 2 );
The second issue is related to how the table view works. The table view manages its cells view's. The width of a cell is defined by the table view's width and the height is defined by the table view's row height property. This means the cell itself has no control over its size.
You can however size its subviews, but you must do this after the cells size has been set (otherwise you can get strange results). You can do this in layout subviews (of the custom UITableViewCell class). See this answer.
- (void)layoutSubviews {
[super layoutSubviews];
self.imageView.frame = ....
}
When layoutSubviews is called the cells frame has been set, so do your view logging here instead of cellForRowAtIndexpath.
As for the GROUPED style. Im not sure if this is designed to work with custom views. I suspect it sets the size of its cells to its own width minus a 20 pixel margin on each size, then applies a mask to the top and bottom cells in a section to get the rounded effect. If you are using custom view try to stick with a standard table view style.