xcode 如何快速在 UICollectionView 中添加分页？

How to add pagination in UICollectionView in swift?

提问by TechChain

I have a UICollection view which shows items. Now I want to add pagination on UICollectionView. I do not want to use any third party for this functionality. Please let me know how I can achieve this!

我有一个显示项目的 UICollection 视图。现在我想在 UICollectionView 上添加分页。我不想为此功能使用任何第三方。请让我知道我如何实现这一目标！

I have four one example http://slicode.com/bottom-refresh-control-uicollectionview/

我有四个一个例子http://slicode.com/bottom-refresh-control-uicollectionview/

But in this I have to drag scrollview upwards for few second to make it work.

但是在此我必须将滚动视图向上拖动几秒钟才能使其工作。

采纳答案by Jaydeep

If you want to add bottom refresh control you have to use below helper class.

如果要添加底部刷新控件，则必须使用下面的辅助类。

https://github.com/vlasov/CCBottomRefreshControl/tree/master/Classes

https://github.com/vlasov/CCBottomRefreshControl/tree/master/Classes

Download this 2 files which is in Objective-C. You have to import this file in Bridging header

下载 Objective-C 中的这 2 个文件。您必须在 Bridging 标头中导入此文件

#import "UIScrollView+BottomRefreshControl.h"

Add refresh control like this.

像这样添加刷新控件。

let refreshControl = UIRefreshControl.init(frame: CGRect(x: 0, y: 0, width: 50, height: 50))
refreshControl.triggerVerticalOffset = 50.0 
refreshControl.addTarget(self, action: #selector(paginateMore), for: .valueChanged) 
collectionView.bottomRefreshControl = refreshControl

This helper class provide you new bottomRefreshControlproperty, which helps you to add refresh control in bottom.

这个助手类为您提供了新的bottomRefreshControl属性，它可以帮助您在底部添加刷新控件。

回答by chirag shah

I have added the functionality of load more in one of my application so let me give you the code

我在我的一个应用程序中添加了更多加载功能，所以让我给你代码

    func collectionView(_ collectionView: UICollectionView, layout
        collectionViewLayout: UICollectionViewLayout,
                        referenceSizeForFooterInSection section: Int) -> CGSize {

        if arrData.count > 0 && isLastPageReached == false
        {
            return CGSize(width:(collectionView.frame.size.width), height: 100.0)
        }
        return CGSize.zero

    }
    func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {

        if kind == UICollectionElementKindSectionFooter {

            let view = collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionElementKindSectionFooter, withReuseIdentifier: "footer", for: indexPath)


            let loading = UIActivityIndicatorView()
            loading.activityIndicatorViewStyle = .gray
            loading.translatesAutoresizingMaskIntoConstraints = false
            loading.tintColor = UIColor.gray
            loading.tag = -123456
            view.addSubview(loading)
            view.addConstraint(NSLayoutConstraint(item: loading, attribute: .centerX, relatedBy: .equal, toItem: view, attribute: .centerX, multiplier: 1, constant: 0))
            vew.addConstraint(NSLayoutConstraint(item: loading, attribute: .centerY, relatedBy: .equal, toItem: view, attribute: .centerY, multiplier: 1, constant: 0))


            return view
        }
        return UICollectionReusableView()
    }

    func collectionView(_ collectionView: UICollectionView, willDisplaySupplementaryView view: UICollectionReusableView, forElementKind elementKind: String, at indexPath: IndexPath) {
        if elementKind == UICollectionElementKindSectionFooter {

            if let loadingView = view.viewWithTag(-123456) as? UIActivityIndicatorView{
                if arrData.count > 0 && isLastPageReached == false 
                {
                    loadingView.startAnimating()
                    self.loadMore()
                }
                else
                {
                    self.isLoadMore = false
                }
            }
        }
    }
    func collectionView(_ collectionView: UICollectionView, didEndDisplayingSupplementaryView view: UICollectionReusableView, forElementOfKind elementKind: String, at indexPath: IndexPath) {
        if elementKind == UICollectionElementKindSectionFooter{

            if let loadingView = view.viewWithTag(-123456) as? UIActivityIndicatorView{
                loadingView.stopAnimating()
                loadingView.removeFromSuperview()

                self.isLoadMore = false
            }

        }
    }

回答by Pranavan Sp

CollectionView Delegate method: Load More data on Scroll Demand on CollectionView.

CollectionView 委托方法：在 CollectionView 上按滚动需求加载更多数据。

func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
        if indexPath.row == numberofitem.count - 1 {  //numberofitem count
            updateNextSet()  
        }
}

func updateNextSet(){
       print("On Completetion")
       //requests another set of data (20 more items) from the server.
}

回答by Shezad

-- itemList- your data array.

-- itemList- 您的数据数组。

-- pageCount- variable used to keep track of the number of pages.

-- pageCount- 用于跟踪页数的变量。

-- totalCount- total number of data

-- totalCount- 数据总数

--- append data to itemListevery time you call the API.

---每次调用 API 时都将数据附加到itemList。

func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
    if indexPath.row == itemList.count - 1 && itemList.count < totalCount{
        pageCount += 1
        // Call API here
    }
}

回答by Ketan Odedra

Easy way to do that

做到这一点的简单方法

 var page: Int = 0
 var isPageRefreshing:Bool = false

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
    YourApi(page1: 0)
}

 func scrollViewDidScroll(_ scrollView: UIScrollView) {
    if(self.mycollectionview.contentOffset.y >= (self.mycollectionview.contentSize.height - self.mycollectionview.bounds.size.height)) {
        if !isPageRefreshing {
            isPageRefreshing = true
            print(page)
            page = page + 1
            YourApi(page1: page)
        }
    }
}

In your api methods

在你的 api 方法中

func YourApi(page1: Int) {
    let mypage = String(page1)
    let request: String = String.init(format:"apiName/%@", mypage)
    print(request)
}

That's it.

就是这样。

回答by Sanjukta

Please try this it works for me.

请试试这个对我有用。

Step 1:

第1步：

Declare a global variable :

声明一个全局变量：

var totalCount : NSInteger?
var isGetResponse : Bool = true
var activityIndiator : UIActivityIndicatorView?

Set the viewDidLoad:

设置 viewDidLoad：

activityIndiator = UIActivityIndicatorView(frame: CGRect(x: self.view.frame.midX - 15, y: self.view.frame.height - 140, width: 30, height: 30))
    activityIndiator?.activityIndicatorViewStyle = .white
    activityIndiator?.color = UIColor.black
    activityIndiator?.hidesWhenStopped = true
    activityIndiator?.backgroundColor = COLOR.COLOR_TABLEVIEW_BACKGROUND
    activityIndiator?.layer.cornerRadius = 15
    self.view.addSubview(activityIndiator!)
    self.view.bringSubview(toFront: activityIndiator!)

Step 2: Set the value in the api call method:

第二步：在api调用方法中设置值：

self.totalCount = array.count
self.isGetResponse = true

Step 3: Write this code :

第 3 步：编写此代码：

func scrollViewDidScroll(_ scrollView: UIScrollView) {


if isGetResponse {
    if (scrollView.contentOffset.y == scrollView.contentSize.height - scrollView.frame.size.height)
    {
        if totalArrayCount! > self.arrProductListing.count{

                isGetResponse = false
                activityIndiator?.startAnimating()
                self.view.bringSubview(toFront: activityIndiator!)
                pageIndex = pageIndex + 1
                print(pageIndex)
                self.getProductListing(withPageCount: pageIndex)
            }
        }

        //LOAD MORE
        // you can also add a isLoading bool value for better dealing :D
    }
}

In service call you can send the page index and from the server end they send back the response.

在服务调用中，您可以发送页面索引，然后从服务器端发送回响应。

Thank you.

谢谢你。

回答by Cemal BAYRI

I used that code while doing pagination. The point is; catching the loaded cell index while collection view is loading and control it's mod with a number and fetch datas seperately with page size field in the api (if there is). You can decide which number will be smaller than this calculation and you will control it.

我在进行分页时使用了该代码。重点是; 在集合视图加载时捕获加载的单元格索引并使用数字控制它的 mod 并使用 api 中的页面大小字段单独获取数据（如果有）。您可以决定哪个数字将小于此计算，您将控制它。

For example you fetched 5 datas and loaded it and, if this state is ok, you will fetch the other 5. Here is the sample code for that.

例如，您获取 5 个数据并加载它，如果此状态正常，您将获取其他 5 个数据。这是示例代码。

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
        if let vc = self.parentViewController as? SellController {
            if vc.dontFetch == false {
                DispatchQueue.main.async {
                    if self.salesData.count > 3 {
                        if indexPath.row != 1 {
                            if indexPath.row % 3 == 1 {
                                print("indexpath: \(indexPath.row)")
                                vc.pagination += 1
                                vc.reload()

                            }
                        }
                    }
                }
            }
        }
    }

In this code i am controlling indexpath.row % 3 == 1 or not. It can be little bit complex so i can share a code block if you want. Good luck:)

在这段代码中，我控制 indexpath.row % 3 == 1 与否。它可能有点复杂，所以如果你愿意，我可以分享一个代码块。祝你好运：）

回答by Naga Syam

The code in willDisplay cellmethod calls load more function while your scroll is 5 cells away from the end. While fetching data show loader in collection view footer. Hide footer when loading is completed.

willDisplay cell方法中的代码调用 load more 函数，而您的滚动距离末尾有 5 个单元格。获取数据时在集合视图页脚中显示加载程序。加载完成后隐藏页脚。

func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {        
        let currentPage = collectionView.contentOffset.y / collectionView.frame.size.width;
        if (aryDataSource.count >= yourAPIResponsebatchCount && aryDataSource.count - indexPath.row == 5 && currentPage >= currentPage && isDataLoading) {
            currentPage++;
            self.fetchMoreData()
        }
        else { }
}