collectionview

问题 I have a UICollectionView and it works fine, but I want to add a few UICollectionViewCells items programmatically into the collection view. So how can I achieve this? To further clarify: when I say programmatically I mean inserting a cell during runtime, when an action is fired, not when the app is loaded (using the viewDidLoad method). I know when the model is updated and the call is made to UICollectionView in the insertItemsAtIndexPaths: method. It should create a new cells, but it's not

问题 I started to use swiftLint and noticed one of the best practices for Swift is to avoid force cast. However I used it a lot when handling tableView, collectionView for cells : let cell = collectionView.dequeueReusableCellWithReuseIdentifier(cellID, forIndexPath: indexPath) as! MyOffersViewCell If this is not the best practice, what's the right way to handle this? I guess I can use if let with as?, but does that mean for else condition I will need to return an empty cell? Is that acceptable? if

问题 I have a custom flow layout which is adjusting the attributes for cells when they are being inserted and deleted from the CollectionView with the following two functions, but I'm unable to figure out how you would adjust the default animation duration. - (UICollectionViewLayoutAttributes *)initialLayoutAttributesForAppearingItemAtIndexPath:(NSIndexPath *)itemIndexPath { UICollectionViewLayoutAttributes* attributes = [self layoutAttributesForItemAtIndexPath:itemIndexPath]; // Assign the new

问题 I'm creating a full screen image gallery using a UICollectionView . When the user rotates the device, I perform updates to the UICollectionView within func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) I present this UIViewController modally and have a UICollectionView taking up the full screen. Within viewDidLoad , I create the flow layout as: let flowLayout = UICollectionViewFlowLayout() flowLayout.scrollDirection = .horizontal flowLayout

问题 I tried many days to realise this: I want to add in my UIViewController two different CollectionView. For example I want to put images in these collectionView Each CollectionView use its own images. Is this possible? I will be very happy if somebody can give me a hand. :) 回答1: This is possible, you just need to add each UICollectionView as a subview, and set the delegate and dataSource to your UIViewController. Here's a quick example. Assuming you have one UICollectionView working, you should

问题 I have to make one collection view so that irrespective of iphone size we have just 2 images in each row and also we need border between each row and column as shown in the image. I want like this: 回答1: Try this code. Just a different approach. func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: IndexPath) -> CGSize { let layout = collectionView.collectionViewLayout as! UICollectionViewFlowLayout layout

问题 When updating a collection of business objects on a background thread I get this error message: This type of CollectionView does not support changes to its SourceCollection from a thread different from the Dispatcher thread. Ok, that makes sense. But it also begs the question, what version of CollectionView does support multiple threads and how do I make my objects use it? 回答1: The following is an improvement on the implementation found by Jonathan. Firstly it runs each event handler on the