Best example for this is the calendar app in Android.
You can scroll down and see upcoming events (dates), if you scroll up you can see past events (dates).
If I want to integrate this in my app, I can easily add pagination when scrolling down and fetch new data. But I am totally lost on how would I add reverse pagination, i.e. when scrolling up, to fetch previous date's data.
Any suggestion ?
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I am currently experimenting with a calendar framework I found online which possesses most of the functionality I need. However, I would really like to add a feature similar to the animation in the iOS Calendar where when a date is tapped, the view splits at that location and the selected week moves to the top of the calendar. Its an intuitive way to display info about the selected day. I just need some suggestions as to how this can be achieved since I'm not super familiar with collection views.
The calendar is a grid collection view with months as different sections from what I understand. Is it possible to just stick a supplementary view anywhere in a collection view dynamically? Or maybe I should look into adjusting insets at a specific location? I'm really not sure what direction to take and could use some suggestions.
Here is sort of what I want to do but with a table view.
I am building a message app. When I am messaging in my application all the messages are getting store in core data. I have connected the core data with TableViewController with NSFetchedResultsController. I know how does this work and I am using NSFetchedResultsController for a long time with TableView. In most of the case TableView load from top and it's scroll down to load more data on requirement, thus my application works pretty well.
Here for the message app the TableView behaviour is opposite from the previous one. It loads the last messages(20-30 batch size) and if I want to see the old message I will scroll top. So I am trying to implement this on NSFetchedResultsController.
Example :
Suppose I have 100 messages. I am setting batch size is 10. So first it will load 90-100 messages and it will scroll down to the last indexpath(here 100th). Then If I want want to scroll top and reach 90th indexpath it will give me 10 again so now I have 80-100 messages now it won't scroll down it will be keep on doing the same thing is I scroll to top.
I know I can sort in reverse order but that time I will get 100-90 but it won't so the last message(100) bellow.
So how can I fix this issue? Any configuration is there for NSFetchedResultsController that I am missing? How to fix?
I'm working on a couple of iOS apps that require the user to select a calendar date, and while the built-in date picker widget is all right, I'd much prefer if users could choose days from a calendar grid, similar to how it works in Hipmunk's iOS app. In that app, users are shown an infinite scroll view showing a grid of days, with each cell showing the month and day. The days of the week are shown in a persistent (i.e. non-scrolling) banner.
In addition to simply showing a calendar, this control should allow dates to be highlighted/selected. Better still, users should be able to select a whole range of dates by tapping on the start and end days' cells, at which the whole range of days should be highlighted.
Any ideas?
It's an "infinite" UIScrollView with various other views inside of it. Apple provides a demo infinite UIScrollview in their StreetScroller project.
You'll be allocating and initializing views for the various things you wanted displayed on each day, and probably reusing views at the top for the dates (as one scrolls off to the left you change the date and move it over to the right, reusing it the way a UITableView traditionally does).
Selection is a matter of changing visible state of the objects that back your views.
I am developing an iOS application that mainly use a UITableView.
It retrieves pages of articles from a server. We have got >25000 articles; so I have implemented a pull-to-refresh and infinite scrolling to travel across the title collection.
The ones downloaded persist using core data; NSFetchedResultsController is used to automatically update the UITableView.
However, I have implemented the infinite scrolling to be in both direction; up and down. Since the user will be allow to scroll down the 25000 article titles, I have to remove the one that the user has already scrolled. If the user scrolls up, I have to re-insert title above the current one.
Doing so, I have got a moving window inside the article collection.
I display my articles by date group using the section and header.
The problem is that because the infinite scrolling goes in both direction, I often delete or add article at a higher position in the table.
Infact to achieve that, I have got to change the predicate associated to NSFetchedResultsController.
This result by scroll being messed up. I have made it jump back to the position where it was supposed to be ish. It is not nice because it is a jump (animation:NO), if I put the animation ON, it goes all around the place before going back to the right position. And the position is not exactly the one it should be.
I am not sure I well explained my problem. I think the problem might be in the way I am using the UITableView but I am not sure how I should use it to make this better.
Cheers
If you only store article titles in Core Data, I think it can handle 25.000 titles.
However I think that the problem you've got is with the pagination of the visible elements of the table
Here is a link that I used to handle something that you requested. You'll have to tweak a little bit to use Core Data and a remote source.
Please post some code if you can so we can have a look.
In my iPad application, i've a scroll view that lists images of 20 video albums. The list of 20 images will be sent by server.
Now when the user reaches end of scroll view, i've to send a request to get next 10 videos details.
After fetching the data, i want to add them to the scroll view at the end. But I want to delete the 10 videos at the beginning. So that at a time scroll view will show only 20 video details all the time.
When user scrolls again to the end, i'll send request to server, get next 10 video details and add them to the scroll view, remove 10 beginning video details from scroll view...... and similarly when user scrolls to the beginning i'll fetch 10 previous videos and repeat the same.
Here i want to make sure the scrolling must be smooth and don't want to have flickers in scroll view. can some one suggest to have better scroll view coding to achieve my requirements please?
If your code contains scroll.pagingEnabled = YES; Then please remove this part of code.
It will surely work.
The real problem here will be in setting up cell recycling. It's not that hard to do, I have a couple examples of which you can look at, one being here. You'll need to make some changes to that code of course, it is set up in "pages" — Only one view on screen at any one time, and I don't think that's what you want.
Aside from that...
Your critical part here will be in designing your data source in a way that allows removing of old items, and adding new items, without skipping items.
For instance, the way I might approach this is to render the "last" item in your scroll view, the same as you want the first item in the scrollview to be. When the user gets to the last item, set your content offset to the start of the scrollview without animation (haven't actually tried this, so there may be a jolt that you don't want, test it and see). This will give the appearance of endless scrolling. Your data source would simply overwrite old indexes when adding new items, instead of adding to the end of an array for instance.
If you are presenting then in the form of a grid view, I suggest you take a look at AQGridView. That grid view supports cell queueing and dequeueing, which does exactly what you describe.
You can also use the delegate method scrollViewDidScroll: to determine if you're at the bottom of the scrollview and trigger the download of the next set of albums.