Assuming I'm on a chat scenario, I want user images to move along with scroll until the other user's messages appear. Some visual example:
I'm using a subclass of UICollectionViewFlowLayout to display the messages and provide that initial left offset for the messages (the sectionInset property is not working on iOS 9 for some reason) and I assumed handling a custom supplementary view to do what's shown above should not be that hard, but apparently it is :)
Some info:
I'm not using standard header/footers for flowLayout since it add a space between sections that I don't want
Found this link which is pretty interesting from performance perspective but the example is somehow incomplete (great post though)
I'm trying to avoid shouldInvalidateLayoutForBoundsChange: to return true and recreate attributes every time since chat cells can be complex in terms of size calculation.
I believe this is not a weird scenario, have anyone accomplish something like this successfully? If so, I would appreciate some pointers.
Thank you in advance.
you can use sections for each cell groups. When using sections they have to be a clear background and be customized. So message cells can be scrolled below sections and circle images on section will be on top of its cells.
As a second way, you can use circle images apart from all collection items. For this, you have to create circle images that how many required. While scrolling up/down, they have to be moved as they will be anchored on top of message cells group.
I hope it helps for you :)
Related
I'm trying to implement the following:
At the top is a segment control that, based on the user's selection (either tapping or scrolling), moves to the relevant CollectionView section.
I've been playing around for a couple of days with CollectionViews and maybe I've just confused myself with LayoutFlows and CompositionalLayouts or is that over complicating it?
I have a diffable datasource that is made up of [Sections, CellItems] but I'm struggling with how to structure it.
What is the recommended programmatic (rather than using interface builder) to do the above? I was just going to originally do 5 horizontal cells, each with a tableView but based on some other comments I've seen from Apple on the Apple forums and the move away from TableView to CollectionView at this year's WWDC, I thought I should be trying to do this properly.
Any direction would be appreciated. All my research seems to point to using orthogonalScrollingBehavior but that layouts out the sections vertically with each section scrolling horizontally.
So my question is should I be trying to do what I'm doing using a CompositionalLayout?
Well first off your segmented control idea makes this sound like you could just use a page control for the horizontal aspect and remove a lot of the collection view complexity. Something to consider anyway.
As for the data source, I think all you need is an array of arrays. Eg. [[CellItems]]. So CellItems[0] would be the first column. Then CellItems[0][0] would be the first cell. CellItems[1][2]... 2nd column 3rd cell. I do apologize as your current solution may be related to diffable datasources and I haven't had time yet to dig into those.
Start with the horizontal axis first and ignore the vertical axis. Get that working as needed. Once you have that up and running... implement another collection view into the first one's cells.
Sorry if I misunderstood the question if it was more about HOW to implement a collection view.
I want to add something like what’s in the app store app:
As you can see, it isn’t just one cell that is paged, but you can also see the two edges of the cells from the left and right as well. I tried to implement this in my app by making each cell slightly smaller than the size of the collectionView, and then enabled isPagingEnabled, but when I flipped from cell to cell, it didn’t page from cell to cell, rather the width of the entire UICollectionView every time. This ended up in an unwanted effect where each page turned resulted in an increasing offset where cells were shifting further and further off the screen.
I researched a bit on this and implemented the targetContentOffset(forProposedContentOffset... but it was never called and didn’t work.
Preferably, I would want to keep the smooth behavior of the built-in pagination and just be able to tweak it.
Thanks!
Instead of implementing the peeking behavior yourself delegate it to a third party library iCourasel. Implementing it yourself you will ended up a UICollectionView inside of UITableViewCell. As of your requirement iCarouselTypeLinear suits your requirement.
I’m still learning to develop in iOS and Swift so I apologize beforehand if my question is too simple.
I have created an UICollectionViewController to show a matrix of elements. My issue is that the width of the screen is not wide enough to fit all the columns in a single row, so the excess of them are shown in another row below. Instead of this, I’d like to enable the horizontal scroll so the user can scroll to see all the columns in one single row.
I know UICollectionViewController already contains UIScrollView so I guess this should be as simple as to change a setting in the .storyboard but I couldn’t find it after many trial-errors :(
I guess it is related to the "Flow" layouts setting and that I need to handle a custom one, but don't know how exactly.
Would anyone be so kind to please help me? I haven’t attached any code because I’m using a pretty standard/out-of-the-box implementation of UICollectionViewController but if you want me to add anything, just let me know, please.
Many thanks in advance for any help!
I found the answer to my issue perfectly covered on this post:
https://www.credera.com/blog/mobile-applications-and-web/building-a-multi-directional-uicollectionview-in-swift/
It's definitely to do with your UICollectionViewLayout — that tells the collection view where everything should go. The collection view simply picks its scroll behaviour appropriately.
A UICollectionViewFlowLayout is a specific type of layout that fills one row column to the size of the enclosing view, then moves on to the next. So it does one-dimensional scrolling. Does that fit your use case?
If so then you should just be able to set the scroll direction on the flow layout.
If not then you'll need to write a custom subclass of UICollectionViewLayout that implements the layout behaviour you want.
I have a screen in my app that pulls an unknown sized array from my user object, and must display an object for each item in the array that consists of a UIImageView for my background image, a UISwitch to activate/deactivate that particular item, a label with the name of the item, and a label that corresponds to the name of the item.
These are displayed in a UIScrollView, since there are nearly always going to be more items than will fit on the screen, especially on the iPhone 4.
I had initially quickly thrown together a static screen that consisted of 20 of these objects, but have found that I will often be exceeding that number of items in the array, and need to convert to a dynamic solution.
I have not used subclassing at all yet, and want to be sure that this is the proper solution before I dive into the implementation. Adding one subclass to my scrollView sounds a lot cleaner than adding each of those components individually and figuring out the spacing for various screens.
If this is the proper solution, are there any resources you could point me to to learn about how to properly do this subclassing? I.e., how to add a constructor for the objects where I can add the contents of the labels and state of the switch, and programmatically add constraints. I've only used constraints from the storyboard.
If you do not think that subclassing UIView would be the proper way to do this, what other solution would you suggest? I'm admittedly a novice when it comes to iOS development, so I apologize that this post seeks advice on where to start rather than help fixing a specific part of an implementation.
You should use UITableView or UICollectionView for that, and subclass UITableViewCell or UICollectionViewCell to create your custom view hierarchy.
UITableView and UICollectionView will handle reusing of cells which will help in memory management.
Update:
as you want to use UITableView so to add spacing between cells set number of sections to number of elements and then add header for section and set its height you can do that by implementing UITableViewDelegates visit below links for detail about UITableView and UITableViewDelegates
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UITableView_Class/
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UITableViewDelegate_Protocol/
I am working on a specific type of list for an iOS app, where cells would simply have a specific width and height and then float left (think of something like CSS float:left), creating then a list that would scroll if more than 12 items (like the picture bellow).
I was thinking that perhaps this could be done by customizing UITableViewCell and setting the frame's width and height, so I could re-use the various benefits UITableViewController, delegate and dataSource offer. but unfortunately it seems that's not possible.
So, I'm now simply creating many UIViews and positioning them across its parent programatically.
I just would like to make sure this would be the right approach to achieve such kind of lists and if someone could let me know if it's indeed not possible to have this kind of functionality on UITableView and inherit all the goodness it offers.
Thanks guys
I know this question is already answered, but still...
I believe you can simply use UICollectionView since iOS 6.0.
Documentation
And this is how it looks like (image)
Maybe this will help somebody.
UITableView can only have cells that go in one direction. It's perfectly okay to create many UIViews (table view cells are also UIViews), if the number of them is reasonable. You can usually have a few hundred UIViews in a scrollview without seeing any performance issues, but that also depends on the complexity of what's inside the uiviews. Try it for yourself and if you find out, that you need too many uiviews, or that their complexity it too high, you can optimize further. You can set the .layer.shouldRasterize property to "cache" the content of the views. Or you can use CATiledLayer, which is something like a UITableView, but it supports tiles in all direction (and scrolling, zooming, ...).
Take a look at this project, I think may be helpful to for your problem
link