How combine UITableView reorder rows with UIDropDelegate - uitableview

Using iOS 11 I'd like a UITableview to support both existing row re-ordering using the standard row drag handle and also accept dropping images via the new UITableViewDropDelegate protocol. Using the standard examples I can accept images using the tableview.dropDelegate working OK,
https://developer.apple.com/documentation/uikit/views_and_controls/table_views/supporting_drag_and_drop_in_table_views?language=objc
but as soon as I assign the dropDelegate, the existing row-reordering no longer works. I tried setting the tableview's dragDelegate and returning an array with single UIDragItem (same doc examples), but this still does not give the existing row re-ordering and the complete cell view can be dragged to "anywhere" in the app, not just in the tableview. Also the animations that show the re-order insertion position do not work.
Any idea if this (combining drag/drop + reorder) is at all possible, or should row re-ordering be handled by the dragDelegate/dropDelegate too? Plus: any example on how to do that?

Related

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

Infinity Scroll and UITableView Data Reload

I'm implementing infinity scroll to load new data in my uitableview that is implemented like Contacts style in Apple embedded App.
My datasource is a IList and then i add new elements on it.
When load new datas to that list if i don't call
this.TableView.ReloadData()
my UITableView doesn't show the new elements added.
That method generates a ugly effect of white screen for a bit, to show next, succesfully, the data added. There are others ways to do that without that effect?
For example using ReloadRows...i can't use that method because i don't understand in which way pass an NSIndexPath[] for rows that aren't loaded yet
You can use the insertrowsatindexpath methods - see the apple documentation at http://developer.apple.com/library/ios/ipad/#documentation/userexperience/conceptual/tableview_iphone/ManageInsertDeleteRow/ManageInsertDeleteRow.html - especially the batch operation section

Push apart TableViewCells while dragging over them. (Similar to UITableViewCellReorderControl)

I want to have a similar functionality like we have with the UITableViewCellReorderControl from the UITableViewCell, but as far as I know I cant use the reordercontrol.
I have implemented Drag & Drop for multiple UITableViews. I can Drag a cell from any TableView to any other. Drag & Drop does work so far. Now I want to push the cells apart when I'm dragging an object over 2 cells, just like Apple does this in Tableviews or when you reorder your apps (the place where you might drop gets empty to indicate the droplocation).
The solutions I thought about are:
1. Insert a placeholder image at the droplocation (this is not so good as I have to sync with CoreData all the time)
2. Change the height of the cell to simulate empty space below it.
I dont think that are the best solutions.

Giving a grouped UITableView "First Crack" at touches when using a section header view containing a control

I am using a standard grouped style UITableView that returns a custom header view for one of it's sections (using the tableView's delegate method viewForHeaderInSection:). The view that is returned for the section header contains a control. It displays an image and is a control so it can tapped to let the user change the image. My desired UI is similar to the photo for a contact in the Apple Contacts app (a floating imageView-like control in a grouped style table).
The problem I'd like to solve is that touches on the tableView section header go straight to the control. I'd like the table to get a chance to determine if the touch is actually the beginning of a scroll gesture. If not, then the table can pass the event to the section header view for processing.
This is how all the rows in the table behave since I have "delaysContentTouches" for the table on. I suspect the problem is because the section header view is not in the table's view hierarchy. So everything is probably working per spec. just not the way I want.
I want the section header view to behave regarding touches just like rows do (table gets first chance to process).
BTW I am not placing this control in a table row (which would solve the problem) because I want the rounded rect grouped style for all table rows, but not for this one UI element. This control is in the center of my table (header for section 1) which is why I want drags on it to scroll the table.
OK, so apparently this is simulator issue only. On a device my tableView gets the first chance at the event. So I guess I need to listen to the Apple mantra of "always test on an actual device" before posting to StackOverflow. Sorry friends... may my error be helpful to others who, like me, probably spend too much time in the simulator.

UITableView Core Data reordering (next)

UITableView Core Data reordering
I'm having troubles with the solution above. If I do updates one by one (ie one move or one delete at a time) it works when back to noedit mode. But with more updates I get application crash. (I'm using a fetchcontroller)
Could someone try this from a tableview not populated :
- create 3 rows
- hit edit mode and move 1st cell to 3rd position, still in edit mode delete the second cell.
- back to noedit mode it crash for me
Besides this I'm trying to make it work in grouped style and with several sections, where you can move cells to any section. Is someone knows an application doing this correctly ?
Thank you
Well after days trying different solutions it seems I finally get what I wanted.
In addition to Ryan Ferretti solution I had to put a flag to bypass tableview updates when commiting moved modifications on CoreData, to get it work with nsfetchedresultcontroller delegate.
It is describe on Apple documentation, see User-Driven Updates : http://developer.apple.com/library/ios/#documentation/CoreData/Reference/NSFetchedResultsControllerDelegate_Protocol/Reference/Reference.html
I now get a tableview grouped style and can move rows from any section to another one, sorted like I want.
So don't forget this flag. :-)

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