Hello as you can see in the video link below when I reload the data, for a frame something happens and some ghost cells appear and disappear, it's like a weird animation... Is it because of using reusable cells? and if it is, is it preventable cause that's not so pretty and it seems to cause a bit of frame drop with use of CATransition animation (not shown in the video). Any help would be appreciated.
Google Drive Link
Video Youtube Link
* EDIT *
Seems the video is not processed by google drive, sorry you gotta download it first to watch it.
Added Youtube link for convenience
Ok I Found the answer myself thanks to all the unnecessary downvotes:
The first solution was to use
collectionView.reloadItems(at: collectionView.indexPathsForVisibleItems)
but that still caused some problem and flicker stuff.
Some other said to use layoutIfNeeded() after that, yet that did not help.
The Solution I Found was to use func reloadSections(_ sections: IndexSet)
so when I use collectionView.reloadSections(IndexSet(integer:0)) (in my case it is the first section) The animation will happen smooth and perfect.
Related
I build chat app using Firebase API right now. I wan't to make preload icons like on facebook screenshot. I thought i can create empty images and label fields and fill them after content loaded, but i don't know how to check if all data loaded from DB. How i can do that in correct way?
This is where i want to place objects
Install ListPlaceholder this lib.
import ListPlaceholder
To show the loader, start showing this from start
tableView.showLoader()
To hide the loader, end showing after data has been loaded
tableView.hideLoader()
Please refer this may get help.
https://github.com/malkouz/ListPlaceholder
Facebook has it's own library called Shimmer. To use this on tableview, you can follow this StackOverflow question answer.
You'll just have to create the UIView you want to animate and above that you'll have to add your FBShimmeringView. At the end set shimmeringView.shimmering = true to start shimmering
To hide the loading use tableView.hideLoader()
ListPlaceholder helped me to resolve the issue. All that I did was added the ListLoader.swift file to my project and added tableView.reloadData(), tableView.showLoader() in viewDidAppear in the tableView where I wanted to show loading.
( ListLoader.swif uses visibleCells to determine the number of rows on which the loading should be shown. In my applications, visibleCell's count was incorrect on calling tableView.showLoader() method in viewDidLoad )
I have a UICollectionView whose cells each have an AVPlayerLayer, all playing a video at the same time. About 9 cells fit on the screen at a time and it's pretty laggy so I need ways to boost the performance to achieve smooth scroll. There's a few things I've tried already:
1) Each cell has only one instance of AVPlayer. It doesn't get created, instead, player.replaceCurrentItemWithPlayer is called when the video url changes.
2) Because I'm using ReactiveCocoa, it's trivial to skip repeat urls to avoid playing the same video twice.
What else can I do to speed up the scroll and performance?
First I want to say it's a bit crazy to see several players in action at the same time: it's a heavy task of rendering anyway.
As far as I know, simply scaling/re-framing the video to smaller size doesn't make it less content to render: if you have a 100x100 picture to render and you render it in a frame of 10x10, it still consumes the same amount of memory as the original picture would consume; same thing goes for videos. So, try to make your video assets having similar resolution as the frame where you would present them.
Store each cell in an NSCache or NSMapTable using the NSIndexPath as the key for each; then, whenever you need a cell, call one directly from the cache or map table.
Obviously, you'll have to create all the cells at once, but you'll get the same scrolling performance as you do with nothing in the cells at all.
Need sample code?
Here's my latest iteration of a perfectly smooth-scrolling collection view with real-time video previews (up to 16 at a time):
https://youtu.be/7QlaO7WxjGg
It even uses a cover flow custom layout and "reflection" view that mirrors the video preview perfectly. The source code is here:
http://www.mediafire.com/download/ivecygnlhqxwynr/VideoWallCollectionView.zip
Unfortunately, UIKit will hit bottlenecks and drop frames when put under pressure for this use case. If you can muster refactoring code to use Facebook's AsyncDisplayKit / then this would be your best bet.
For objective-c / this project here is a good reference.
https://github.com/TextureGroup/Texture/tree/master/examples/ASDKTube
- (ASCellNode *)tableNode:(ASTableNode *)tableNode nodeForRowAtIndexPath:(NSIndexPath *)indexPath
{
VideoModel *videoObject = [_videoFeedData objectAtIndex:indexPath.row];
VideoContentCell *cellNode = [[VideoContentCell alloc] initWithVideoObject:videoObject];
return cellNode;
}
there is swift code available if you dig deep enough in github.
Anybody having issues tapping on cells where a lot of cells exist? I keep getting the error "Failed to get refreshed snapshot".
I tried using the recorder but that also seems to freeze. I assume it's trying to cache all the cells in the view.
Example: I have cells for each day on a calendar with accessibilityIdentifiers. I have no problems tapping on the cells using the Identifiers with KIF.
Yes, i have. Its about 1 error of 100 tests. Maybe is an apple bug: https://forums.developer.apple.com/thread/6437. I don't know any workarounds :(
A work around would be to tap screen coordinates as mentioned by taylesworth on Apple Developer Forums
Example:
let coordinate = cell.coordinateWithNormalizedOffset(CGVector(0.5, 0.5))
coordinate.tap()
I have been developing my app for iOS8, and haven't really had any issues regarding the scrolling speed. The moment I have upgraded to iOS9 the collectionView became very jumpy and staggering. I cant point out to any specific reason why. In my collection view, I have items with images that uses 3rd party library (SDWebImage) and I also use a custom layout library to achieve double column layout. Is there any obvious reason why this could be happening?
We were experiencing the same issues with collection views with iOS 9. The cells also contained images from SDWebImage including animated GIFs. It turned out not to be an issue with SDWebImage but with auto layout. If you have layout constraints with <= or >= inside your UICollectionViewCells (particularly on UITextViews, but still visible on UILabels, iOS 9 just chugs. Hope this helps someone.
In this case the problem was about handling fallback images on the imageView.
Briefly, each item in the CollectionView has an UIImageView. Each UIImageView has a fallback image in case the actual image doesnt resolve (the url is broken for example). So, the way these fallback images set was wrong in my app! I have set images every time a collectionview item is rendered in the viewport.
UIImageView * fallback = [UIImage imageNamed:#"imageName"];
was called everytime, which makes the scroll staggered. Interestingly it wasnt an issue on iOS8 but only in iOS9.
So when I started reading from a precreated dictionary of images instead of creating a new one every time, the scroll view started become smooth again.
Hope this helps to those having the same issue.
I have been working on an app that uses UIDynamics in UICollectionView. I have watched Apple WWDC video and have also tried this sample app in Github.
However, I had this weird problem: When my app launches, I set the number of items for my collection view to 0, the app needs to download something from the server then populate the collection view on the main thread. Weirdly, it's (kinda) reloaded, but not showing anything. I tried on the sample app from Github and it has the same issue as well.
However, if I remove this part:
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect{
return [self.dynamicAnimator itemsInRect:rect];
}
The CollectionView will show what I want but without the UIDynamics.
I hope the illustration on my problem is easy to understand. Any help will be much appreciated. My guess is I shouldn't use reloaddata.