What's the point of this contentView property? I mean: Why aren't all the subviews just added to self?
Let me get that right: Every cell is a view (UITabvleViewCell is a UIView subclass). And this fat view has another fat view with same bounds sitting on top of it, called contentView. That contentView then carries all those other subviews.
Now why didn't they save that extra chunk of memory? Is there any genius logic behind this decision? Would love to understand the reason for this.
The content view does not always have the same bounds as the cell. For instance, when entering editing mode, the delete button slides the content view to the right, resizing it in the process.
From A Closer Look at Table View Cells
Figure 5-1 Parts of a table view cell:
Figure 5-2 Parts of a table-view cell in editing mode:
Related
Below attached image is representing my requirement:
In this image the yellow color UITableView will have list of different UITableViewCell items. In one of the UITableViewCell it has UICollectionView with its list of UICollectionViewCell items and the scroll direction for the UICollectionView is set to horizontal
Each UICollectionViewCell will have one UITableView (Highlighted in Red Color) and it will have its list of UITableViewCell (Highlited in Rose Color) items. Here, the UITableViewCell (Highlited in Rose Color) item can collapse/expand. Whenever the cell is collapse/expand the red table's content size is handled automatically. But, whenever the red table's content size is increased the collectionview size is not increasing.
I have added all relevant constraints to these UI elements. But, the content size or frame of the collectionview is not expanding when a tableview cell is expanded.
To understand better here i am breaking it down how the views are designed:
Yellow tableview embedded inside a UIViewController and it will have one simple UITableViewCell which has no custom class
To the cell programatically the UICollectionView will be added. This UICollectionView is placed in one xib file and it has embeded inside a UIView
UICollectionViewCell has been created in one xib and it will have UITableView element inside.
Also, UITableViewCell has its own xib to refer and this is the cell which will gets expand/collapse
I have tried modifying the intrinsicContentSize property to modify the UICollectionView property's height where it has embedded inside UIView element whenever the expand is happening. Please, refer the CardView.swift for the reference.
CardView.swift
I know the design is bit complex. But, what am i missing here?
Based on your requirement in the image, I just created a sample project here.
I did not use separate Xibs. However, I was able to achieve what you asked for.
You might have to handle the reload of the innermost tableView better based on your apps business logic.
Here's what I have implemented:
The top most view controller has a parent table view.
This table view cell consists of a child collection view.
The child collection view cell consists of a grand child table view.
The grand child table view is the one corresponding to the table view Highlited in Rose Color in the question.
To answer your question about the collection view not expanding: to expand the child collection view when the grandchild table view cell is tapped, I am reloading the parent table view by increasing the row height for the cell containing the collection view. Hence you don't have to worry about adjusting the constraints in auto layout
In case you want to add additional content into the child collection view cell, you can add a height constraint to the grand child table view with a low priority and modify that whenever you need to expand the content in the grand child table view.
if you want to achieve point 6, as suggested by #Ramy Al Zuhouri, you might have to call: collectionView.performBatchUpdates before collectionView.reloadData() to expand the cell size
Refer to the video below for better understanding
This doesn't necessarily solve your problem, but sometimes it's a matter of forcing the collection view to invalidate its layout and recalculating its size. I once received an answer to a TSI from an Apple enginner:
So this is old fashioned way of forcing a re-usable container (Collection || Table) to invalidate its layout. You may even be able to just call invalidate layout. There are oddities in the system with AutoLayout and animations that sometimes throw the system into an odd state. If we do the above the container and can invalidate its layout and make updates without need to re-calculate + incorporate animations. To summarize, calling performBatchUpdates with nil parameters can be useful if you need to force an update based on layout content (not necessarily datasource changes).
It looks like a hack to be used with caution, but it can be worth to give it a try. Whenever you need to recalculate the size of the collection view's cell to expand or shrink, you can do this:
UIView.setAnimationsEnabled(false)
collectionView.performBatchUpdates(nil, completion: nil)
UIView.setAnimationsEnabled(true)
collectionView.reloadData()
This forces a reload, and UIKit is able to recalculate the height of the cell given that you update the height. How? In my case I did by updating a height constraint, but there are multiple ways of doing this. However, it's intended that as the reload happens the collection view should be aware of the new cell height.
the good approach for this, you have to add collectionView in the tableViewHeader
then whenever you scroll up your tableView your collectionView section will also scroll up
to load cells on the specific indexes follow bellow steps:
if(indexpath.row == 0){
//load first tableView cell with collection view
}
else if (indexpath.row == 1){
//load second tableView cell with collection view
}
else{
//load table view cell here
}
This question already has answers here:
Programmatically send to front/back elements created from interface builder
(2 answers)
Closed 10 days ago.
I am using a .xib for my cell in a table view. Inside the .xib, is another view (cellBackgroundView), and a button. When I run the app, and click the button, it does not respond at all. Instead, it calls the tableView's didSelectedRowAtIndexPath method which brings another view controller.
Using Xcode's Debug View Hierarchy, I discovered that I have a view overlaying the all the buttons (see pic attached: this overlaying view is highlighted). This view (called backgroundView) that is overlaying my button is a View, within a view. I have a feeling when you place a view in a view, and put a button in the initial view, the button isn't called because its below the view hierarchy.
How do I fix this issue? Is there a way to move background view to the back of the view heirarchy so that the buttons will be responsive?
Debug View hierarchy:
Structure of .xib
Two things that you could check
1) Do you have a delegate method for cell height and is the height returned correct? Unless you have Clip Subviews on for the UITableViewCell, the contents of the cell can be visible outside it's frame, but the parts that are outside the cell's frame are not registering user interactions.
2) Is some other view element higher in the hierarchy (lower in the XCode listing you posted) overlapping the button? iOS Simulators Debug -> Color Blended Layers can help spotting this.
Edit:
If I interpret the added screenshots correctly, you probably have the issue mentioned in the option 1) above. If the other elements showing in the screenshot are those listed as subviews of the Cell Background View they are mostly outside the parent view's frame and thus don't receive touch events. If the background view's frame is correct, then you might want to move the other elements as children for Feed Cell directly.
Also, the element listing suggests that you are using plain UIView as the parent element. I don't know the inner workings of your application, but if you only use this view in a UITableViewCell you might want to consider making the parent view a Table View Cell in the xib. This will reduce some bloat and allow you to configure some properties for the cell in the xib.
Maybe you forgot assign your Button to code
I assume Feed Cell is a subclass of UITableViewCell, and cellBackgroundView is the property contentView of this cell.
If so, the cells property backgroundView should be behind your cellBackgroundView (the docs say: UITableViewCell adds the background view as a subview behind all other views and uses its current frame location.).
You could set the cells property backgroundView = nil, and see whether it is still there in the view hierarchy. If so, you do add a custom backgroundView on top of the other cells views somewhere.
To check this, you could read out the subview hierarchy of your cell in your method tableView:cellForRowAtIndexPath: with something like NSArray *svs = cell.subviews; (assuming cell is the tableViewCell) and set a breakpoint behind this statement.
svs usually contains first the UITableViewCellContentView, and above it the _UITableViewCellSeparatorView. The cells backGroundView will not be shown. You could check there your view hierarchy.
If by chance there is a custom backgroundView on top, you could - as a workaround, not a solution - bring the contentView to the front by sending to the cell bringSubviewToFront: with the contentView as argument. Then the button should respond.
In your Structure of Xib Place your button below the view that is first the view is added to superView then the Button, then your button will work.
or you can code
-(void)viewDidLayoutSubviews{
[self.view insertSubview:yourButton aboveSubview:cellBackgroundView];
}
Hope it will help.
Do you add an UIButton by code?
If so you should ensure you addSubview: into cell.contentView and not into cell.
Also you could try to apply CellBackground class to a view inside contentView, not directly to contentView.
you can use this method.
[cell.contentView bringSubviewToFront:yourButton];
after that if you want to back in background then tou can use sendSubviewToBack: method .
After adding this methods your button is not responding set the userIntractionEable of button's superview.
I am trying to add collection view to UIView and there is a problem that doesn't make any sense. Screenshot. I made the background color of the collection view, to make show the view area more clearly.
If I add the collection view straight to the controller (just like in UICollectionViewController), the top padding doesn't exist.
In this example, I have autolayouted the collection view to resize to the whole view but the problem existed the moment I added collection view to the UIView.
Also, if I add another collection view right after this view, there items start from the top, without any margins.
If there is anything else you need me to provide, I will do it. I think this is a storyboard bug or something because there are no insets, in the view's attributes.
I am working in a profile ViewController. This profile has a main image in a UIView subclass and a CollectionView gallery with some images. I would like to be able to scroll up the UICollectionView and move the UIView too, and if I scroll down, I want to watch again the UIView when the collectionView first item is showed again.
I have tried to do this adding the collectionView and the UIView to a ScrollView, but the UIView only scroll up if I touch it.
In this picture you can see my problem
Thank you in advance
You need to make the view at the top a Header View of the collection view.
Essentially it needs to be an actual part of the collection view if you want this action. (That's the easiest way anyway).
So the collection view will take up the whole screen but it will have a header view. Then when you scroll the collection view the header will move out of view and then come back in when you scroll down again.
I have added a subview to my tableview and when ever the user scrolls the tableview, the subview scrolls with it. How do I prevent this? I know it's probably along the lines of not adding the view to the tableview's subviews, but I have no knowledge of any other ways to do this. Thanks.
If you want to make a view a subview of the table view, then you can make it floating (non-scrolling) by changing its origin.y value in the scrollViewDidScroll method.
-(void)scrollViewDidScroll:(UIScrollView *)scrollView {
self.iv.frame = CGRectMake(self.ivOrigin.x, self.ivOrigin.y + self.tableView.bounds.origin.y, self.iv.frame.size.width, self.iv.frame.size.height);
}
In this example, "iv" is a property for an image view, and "ivOrigin" is a property for the initial origin of the image view (defined when I created the image view and its frame in viewDidLoad).
The UITableView is built and intended to be a view of things that scroll.
So, you can either fight that, which as you're discovering is quite hard since everything about the component is built and focused around scrolling and fast display of a subset of the full list data... Or, you can not fight it and put your static item on top of the table as a fixed-position item.
If there's a reason you can't add the table view and your animate-out item in your main view, you can always add a custom UIView class that contains both the table view and your animated view. Have your custom view class expose the contained table view as a .table property, and the container you're putting things in can be tweaked to use "mycontainerObject.tableview" instead of just "tableview" where needed.
Yes, it's a little more work to write the custom UIView subclass and give it a couple properties to hold the UITableView and whatever UIView you're animating out.. but it's likely a lot safer in the long run than trying to "hack" into the UITableView's methods and view hierarchy to try to give it a "fixed in place" behavior.