xcode Swift 4 UICollectionView 检测滚动结束
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Swift 4 UICollectionView detect end of scrolling
提问by Rexhin Hoxha
I have an HorizontalUICollectionViewon my app and I want to load more data when the user reaches the end (or nearly to the end) of UICollectionView while dragging on the left.
我的HorizontalUICollectionView应用程序上有一个，我想在用户在左侧拖动时到达 UICollectionView 的末尾（或接近末尾）时加载更多数据。
I'm using Swift 4. I found some Swift 3 solutions but they do not work for me.
我正在使用 Swift 4。我找到了一些 Swift 3 解决方案，但它们对我不起作用。
My current code is:
我目前的代码是：
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return self.videoViewModel.images.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionViewCell", for: indexPath) as! CollectionViewCell
cell.imgImage.image = self.videoViewModel.images[indexPath.row]
return cell
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
updateVideo(data: self.videoViewModel.relatedVideos[indexPath.row])
}
回答by Fayza Nawaz
You may use cellForItem or willDisplayItem methods of collection view. Check if the last cell is being displayed, and load your data. For example:
您可以使用集合视图的 cellForItem 或 willDisplayItem 方法。检查是否正在显示最后一个单元格，并加载您的数据。例如：
Swift:
迅速：
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
if (indexPath.row == dataSource.count - 1 ) { //it's your last cell
//Load more data & reload your collection view
}
}
Objective-C:
目标-C：
- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath {
if (indexPath.row == dataSource.count - 1 ) { //it's your last cell
//Load more data & reload your collection view
}
}
回答by Ilya Kharabet
Implement method scrollViewDidScrollof UIScrollViewDelegate:
实现方法scrollViewDidScroll的UIScrollViewDelegate：
var isLoading: Bool = false
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let contentOffsetX = scrollView.contentOffset.x
if contentOffsetX >= (scrollView.contentSize.width - scrollView.bounds.width) - 20 /* Needed offset */ {
guard !self.isLoading else { return }
self.isLoading = true
// load more data
// than set self.isLoading to false when new data is loaded
}
}
回答by iVarun
Take one bool variable and one integer variable for page number like this:
取一个布尔变量和一个整数变量作为页码，如下所示：
var isDataLoading = false
var pageCount:Int = 1 // Pass this page number in your api
in cellForItemAt method add below code:
在 cellForItemAt 方法中添加以下代码：
if !isDataLoading && indexPath.row == videoViewModel.count - 1 {
isDataLoading = true
pageCount += 1
// add you api call code here with pageCount
}
once you get your data from api set isDataLoading bool to false like below:
一旦你从 api set isDataLoading bool 到 false 获取数据，如下所示：
self.isDataLoading = false
回答by Zain Shahzad
This is simple login which will go down to last index...!!!
这是一个简单的登录，它将下降到最后一个索引......！！！
func ScrollEnd() {
let lastSectionIndex = (self.collectionView?.numberOfSections)! - 1
let lastItemIndex = (self.collectionView.numberOfItems(inSection: lastSectionIndex)) - 1
let index = IndexPath(item: lastItemIndex, section: lastSectionIndex)
if messages.count != 0{
self.collectionView!.scrollToItem(at: index, at: UICollectionView.ScrollPosition.bottom, animated: false)
} }
回答by Krishna Srivastava
Add this in your collectionView willDisplayCell delegate
将此添加到您的 collectionView willDisplayCell 委托中
if (indexPath.row == dataSource.count - 1 ) {
//it's your last cell
//Load more data & reload your collection view
}
