To use Flow Layout, or to Customize? - ios

I'd like to build a collection view layout as outlined in the diagram below.
Primarily, I'd like to keep all items for a particular section on the same line. When the users scrolls vertically, the sections scroll off the page. When the user scrolls horizontally, the items left and right ("tucking" under the section header when scrolled left, bringing new items on screen from the right).
I understand Apple says "If it looks like a grid, you can use Flow Layout," but I'd like to understand if that's just a blanket statement, or if the above will push the limits.
Can layout above be done using the FlowLayout, or am I better off building a custom layout from scratch?
If you're a guru with layouts and this is "child's play," I'd love to see an example of how to proceed.
Thanks!

You need to use layout class which will inherit UICollectionViewFlowLayout. By doing this, you can customise your behaviour of layout by using below methods. Also you can get all hooks of Flow Layout also.
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect; // return an array layout attributes instances for all the views in the given rect
- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath;
- (void)prepareLayout;

Rather than going to the trouble of creating a custom UICollectionViewLayout subclass, you can achieve the behavior you're looking for by using a standard table view, with a cell for each row that contains one view for the header, and a horizontally-scrolling collection view for the row items.
I put together a little example that you can download here.
A little extra work is needed to maintain the scroll position of the collection view as you scroll vertically through the table view, so I'm saving that into an instance variable, and restoring it when the table cell is requested. Other than that I think the example project is fairly straightforward.

Here is my implementataion! Hope this will help you!

You cannot subclass UICollectionViewFlowLayout here because it is a single-line based layout.

Thanks for the excellent answer. It works for me. You can also specify one single line per tableview section and add header section for each collectionview.

Related

Paging through different diagrams in a table view cell

I'm looking for a method to page or slide through up to 6 different views in one table view cell. What's the best approach to do that?
I already experiment with a Collection View and a Page View Control. But the diagrams are represented by different classes, so that the standard tutorials setting up a label, are not working for me.
Thank for any feedback on this topic.
Based on what you are doing, I would use a UICollectionView with different UICollectionViewCells for your different diagrams. That should allow you to use different classes for the content of each cell.
So first go and create a UICollectionViewCell for each diagram.
Then you are going to want to go into your UICollectionViewController (or wherever you are implementing your collection view) and in the cellForItemAtIndexPath method tell it which cell to display for each indexPath.

When to use UICollectionView instead of UITableView?

I found that UICollectionView is like an upgraded version of UITableView introduced in iOS6, but when should I choose UICollectionView instead of UITableView?
There are still Apps using UITableView, if UICollectionView can do anything UITableView can do , why people still use UITableView? Is there a difference as far as performance is concerned?
Thanks!
That depends on the requirements. How the application flows determines which type of UI to integrate into the application.
People mainly use the UICollectionview for creating types of UIs with multiple images shown in a grid. This would have complex logic using UITableView, but with UICollectionview, it would be easy.
When using UICollectionview, you don't need to set buttons with tags or other things by getting selected items values. You can simply get -(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath and in UITableViewDelegate:
`-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath`
You get the selected row instead of the item, so for creating grid or modified items, using UICollectionview is best.
For the listing details of each item, people use UITableView because it shows more info on each item.
Apple Docs:
UICollectionView Class Reference
The UICollectionView class manages an ordered collection of data items and presents them using customizable layouts. Collection views provide the same general function as table views except that a collection view is able to support more than just single-column layouts. Collection views support customizable layouts that can be used to implement multi-column grids, tiled layouts, circular layouts, and many more. You can even change the layout of a collection view dynamically if you want.
UITableView Class Reference
A table view displays a list of items in a single column. UITableView is a subclass of UIScrollView, which allows users to scroll through the table, although UITableView allows vertical scrolling only. The cells comprising the individual items of the table are UITableViewCell objects; UITableView uses these objects to draw the visible rows of the table. Cells have content—titles and images—and can have, near the right edge, accessory views. Standard accessory views are disclosure indicators or detail disclosure buttons; the former leads to the next level in a data hierarchy and the latter leads to a detailed view of a selected item. Accessory views can also be framework controls, such as switches and sliders, or can be custom views. Table views can enter an editing mode where users can insert, delete, and reorder rows of the table.
Here's my criteria:
If a UITableView can do it, use it
If a UITableView needs lots of code to do it or can't do it at all, use UICollectionView.
You have to consider the restrictions on UITableView before making a decision: It's a single column. And you can only customize the cells, but not section backgrounds and such. So if you have a straight-up list of things with no extra frills - that looks like a bog standard iOS view, basically - then use UITableview. If you have custom insets, or a border around each section, use UICollectionView.
I'm actually considering UICollectionView for all things simply because it's very expensive when you start developing your view as a table view, then later find out it can't do that one thing that you need it to do. 1st hand experience ;)
Edit after even more experience with the two: Disregard that last paragraph. UICollectionView requires a lot of boilerplate code to make it work like a UITableView. Use UICollectionView only when really needed. ;)
For simple lists and forwards/backwards navigtaion, use UITableView.
If you need a high degree of customisability, use UICollectionView.
Generally speaking, in software development, it's best to choose the approach which represents "The Simplest Possible Thing".
EDIT: As of iOS 14, UICollectionView can now do lists as well and is now the recommended approach. See this session from WWDC20 for more information and implementation details: https://developer.apple.com/videos/play/wwdc2020/10026/
According to my point of view main difference between collectionView and tableView is that
TABLEVIEW --> show list of items in only one column.
COLLECTION-VIEW -->show list of items in multiple column.
Hope it will help you.
If you choose UITableView for iPhone, make sure you have considered your iPad strategy first. If you want an iPad-specific layout, you may want that single-column layout to become a grid.
Although it's not required, I always use a collectionview. That way I can easily adapt how my collections are presented for differing resolutions. A plus is that it's ready to quickly add new types of cells when refactoring in the future.
I see no point of tableviews. It's very simple to use a collection view to represent a table. IMO.
From my personal experience the two elements should only be compared loosly.
TableView
A TableView is a UI element designed for showing data in a list format. There is certain functionality that comes as standard with a UITableView, such as:
Accessory View
Cell Selection Style
Editting Style (Delete and edit buttons).
The above elements enhance the usability of data when displaying and interacting in a list format. Such as viewing emails.
CollectionView
A CollectionView is a UI element designed for showing content using a custom layout (usually anything that isn't a list). CollectionViews improve functionality of displaying data in completely bespoke layout styles and also dynamically changing layouts on the fly. Some examples are:
Horizonal Lists
Photo Galleries
Thumbnail views
Carousels
Dials
Laying out elements on a map
etc.
CollectionViews also allow for multiple selections.
Conclusion
As you can see from the above, both have completely different use cases and are designed for enhancing the development and usability of their own specific data sets.
If you are looking at displaying anything in a list style with the followin interactions:
- Adding
- Deleting
- Re-ordering
Then a UITableView will simplify this process by providing the support straight out of the box.
Anything else, you should leverage the benefits of CollectionView as you have more flexibility.
Its totally dependent on how your data to be shown.
As mentioned by many above, if you require only single set of data and that too not complex, go for UITableView else use UICollectionView.
UICollectionView is customization friendly.
If you are dealing with multiple cell heights or so, then go for UICollectionView.
Both are depends on the requirements. Table Views also have support for a variety of editing scenarios. This support has not been implemented in the Collection View classes.
If you are converting from a Table View that relies on these methods, expect to do a little extra heavy lifting in the Collection View.
Collection View section headers can be placed anywhere within the view.
and UITableView don't need to set buttons with tags or other things by getting selected items values.
In practice, everyone uses UICollectionView that I've come across, when they only need a UITableView. "It's one-dimensional. It goes up and down. Why are you adding unnecessary delegate methods for layout AND data?". I once spent an extra 2 hours helping a startup find out why their UICollectionViewCell got squished because the owner, who didn't read the Animations manual, nor HIG, nor the UICollectionView guide, decided to use it and add variable heights and anims. Needless to say, he gave himself a headache and much lost time on a non-business-critical issue he could have avoided by simply using a table cell, since there's no extra layout delegate + Nib.
Let me get this straight, I am all for UICollectionView's when your data and display need it. They're very powerful. But in practice, most people I've seen have been using them on lists.
This brings up another flaw. They're also used on short, constant lists that won't change, ever. In this case, just make a Xib. Or write a custom view that stacks them. Why? Because you don't need the memory management for 5 sets of labels with a button or switch. If they might change, then yes, use a list. If you want physics, then UICollectionView works well with a some cool effects. But do you really need to add 5 delegate methods and a layout system for 5 labels that will never move?
Also, I'm not forgetting that iOS has a native stacking view now too. I can never get it to deform how I want, even though I'm quite adept at the 2D and animation systems, so I never use the built-in one.
All I'm saying is, define your requirements. Maybe you don't need either of these, if your UI isn't adding/removing items and refreshing itself. Or maybe you want to write a Card Game and throw them out virtually on a table, then use UICollectionView with a physics system for its layout guide.
Personally I think the UICollectionView can do most of the work which UITableview can do. well, at the same time, it's more complex to use.
I suggest you use UICollectionView as TableView just in case your manager change requirements in the future.
Based on our need we are choosing TableView or CollectionView.
Example:
For phone contacts tableView is best option.
For photo gallery, collection view will be best option.
I had this issue in my current project. Which to use. In my case it was simple really. I needed both. I needed my view to look like UITableView and also to change its change / layout. So, UICollectionView was used. I also use UITableView everywhere I don't need any extra customisation. Since UiTableView comes with a default layout that includes images and text - I use it for simplicity.
Based on our requirement we choose UITableView or UICollection view.
If we want to display images or items in grid type or if we need more customisability we use UICollectionview.
For listing each item with details and subdetails we use UITableView.
UICollectionView:
The UICollectionView class manages an ordered collection of data items and presents them using customizable layouts. Collection views provide the same general function as table views except that a collection view is able to support more than just single-column layouts.
UITableView: A table view displays a list of items in a single column. UITableView is a subclass of UIScrollView, which allows users to scroll through the table, although UITableView allows vertical scrolling only.
As per my view for Grid View display use UI Collection View.All other list view use UITable View

iOS UI - Toggling between UICollectionView & UITableView in one screen

The question is hopefully pretty straight forward. In one of the tabs of my application where I'm presenting a set of data from Core Data, I want to give the user the option of a Grid view or Table view. Both views should share the same custom header with a button in the header that let's them toggle.
I see it in other apps all the time, but couldn't return any searches. I'm getting stuck on how to flip between the 2 controllers based on different classes.
Any help or guidance is much appreciated. Thanks a lot!
Assuming you are using a UICollectionViewFlowLayout, just adjust the itemSize property of your items to be the width of their containing view.
Bam. Instant "table view"
Sure, it's not quite a tableView, and reasonable people can disagree over when a tableView might be more appropriate than a collectionView, but for what you describe (giving the user a choice between rows or grid), it's probably the magic bullet you seek.

Dynamic uiview layout with auto layout

I'm working with autolayout and its been going very well so far but right now I am at lost as to the way to proceed to achieve the design I want.
I got a a small questionnaire with 2 sections. Each section is embedded in its own UIView with each section's view containing an uiview per question.
My problem is, I want to add the question dynamically, say only show question 2 of section 1 when the user enter a certain input in question 1.
I first attempted to show each section by using using addsubview for the question view and reseting the frame of the section dynamically using setFrame: before realizing this method was not gonna work properly with autolayout (for example, since my questionaire is contained in a scrollview, scrolling will call the loadsubviews method on the scrollview and reset the section's view to their original size...)
What would be the proper way to achieve this? Using a tableview with a variable size perhaps? Or programatically creating layoutconstraint?
What I ended up doing is Dan F suggestion of using a tableview. I used the answer in this great post https://stackoverflow.com/a/12574544/865632 to create static tableview in view container allowing me to have static cell uitableview without having to cluster my main view controller with dummy tablecontroller

UITableView with a plain listing but make the section header be like a grouped listing

I am using a UITableViewController with a plain style. I like how the cells expand to the edges of thew view, but I hate how the section titles stick to the top.
Is there a way to have section titles behave similar to how a grouped listing works?
What about using grouped style but removing the left and right margins. Possible?
I think this question might answer you. One awkward way of achieving this is not using the UITableView sections and draw cells instead with your a custom design.
You could always create a custom cell with the appearance of a section header. That's what I've done in the past to for these kinds of scenarios, that way it won't stick to the top of the view. This of course requires additional logic such as disabling section headers and and using your new custom section header as a single celled section in your table view, if you catch my drift. It's actually not that hard and gives you good flexibility.

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