UITableView 在像 Facebook 应用程序一样滚动到底部时加载更多

Question

我正在开发一个使用 SQLite 的应用程序。我想使用分页机制显示用户列表（UITableView）。谁能告诉我当用户滚动到列表末尾时如何在我的列表中加载更多数据（比如在 Facebook 应用程序的主页上）？

Answer 1

您可以通过在cellForRowAtIndexPath: 方法中添加对您所在位置的检查来做到这一点。此方法易于理解和实现：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Classic start method
    static NSString *cellIdentifier = @"MyCell";
    MyCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
    if (!cell)
    {
        cell = [[MyCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:MainMenuCellIdentifier];
    }

    MyData *data = [self.dataArray objectAtIndex:indexPath.row];
    // Do your cell customisation
    // cell.titleLabel.text = data.title;

    BOOL lastItemReached = [data isEqual:[[self.dataArray] lastObject]]; 
    if (!lastItemReached && indexPath.row == [self.dataArray count] - 1)
    {
        [self launchReload];
    }
}

编辑：添加了对最后一项的检查以防止递归调用。您必须实现定义是否已到达最后一项的方法。

EDIT2：解释 lastItemReached

Answer 2

斯威夫特

方法一：滚动到底部

这是Pedro Romão's answer 的 Swift 版本。当用户停止滚动时，它会检查它是否已到达底部。

func scrollViewDidEndDragging(scrollView: UIScrollView, willDecelerate decelerate: Bool) {

    // UITableView only moves in one direction, y axis
    let currentOffset = scrollView.contentOffset.y
    let maximumOffset = scrollView.contentSize.height - scrollView.frame.size.height

    // Change 10.0 to adjust the distance from bottom
    if maximumOffset - currentOffset <= 10.0 {
        self.loadMore()
    }
}

方法2：到达最后一行

这里是shinyuX's answer 的 Swift 版本。它检查用户是否已到达最后一行。

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    // set up cell
    // ...

    // Check if the last row number is the same as the last current data element
    if indexPath.row == self.dataArray.count - 1 {
        self.loadMore()
    }

}

loadMore() 方法示例

我设置了这三个类变量来获取批量数据。

// number of items to be fetched each time (i.e., database LIMIT)
let itemsPerBatch = 50

// Where to start fetching items (database OFFSET)
var offset = 0

// a flag for when all database items have already been loaded
var reachedEndOfItems = false

这是将更多项目从数据库加载到表视图中的功能。

func loadMore() {

    // don't bother doing another db query if already have everything
    guard !self.reachedEndOfItems else {
        return
    }

    // query the db on a background thread
    DispatchQueue.global(qos: .background).async {

        // determine the range of data items to fetch
        var thisBatchOfItems: [MyObjects]?
        let start = self.offset
        let end = self.offset + self.itemsPerBatch

        // query the database
        do {
            // SQLite.swift wrapper
            thisBatchOfItems = try MyDataHelper.findRange(start..<end)
        } catch _ {
            print("query failed")
        }

        // update UITableView with new batch of items on main thread after query finishes
        DispatchQueue.main.async {

            if let newItems = thisBatchOfItems {

                // append the new items to the data source for the table view
                self.myObjectArray.appendContentsOf(newItems)

                // reload the table view
                self.tableView.reloadData()

                // check if this was the last of the data
                if newItems.count < self.itemsPerBatch {
                    self.reachedEndOfItems = true
                    print("reached end of data. Batch count: \(newItems.count)")
                }

                // reset the offset for the next data query
                self.offset += self.itemsPerBatch
            }

        }
    }
}

Answer 3

最好使用willDisplayCell 方法来检查是否将加载哪个单元格。 一旦我们得到当前的indexPath.row 是最后一个，我们就可以加载更多的单元格。 这将在向下滚动时加载更多单元格。

 - (void)tableView:(UITableView *)tableView 
       willDisplayCell:(UITableViewCell *)cell    
       forRowAtIndexPath:(NSIndexPath *)indexPath
{
    // check if indexPath.row is last row
    // Perform operation to load new Cell's.
}

Answer 4

详情

• Swift 5.1，Xcode 11.2.1

解决方案

使用 UIScrollView / UICollectionView / UITableView

import UIKit

class LoadMoreActivityIndicator {

    private let spacingFromLastCell: CGFloat
    private let spacingFromLastCellWhenLoadMoreActionStart: CGFloat
    private weak var activityIndicatorView: UIActivityIndicatorView?
    private weak var scrollView: UIScrollView?

    private var defaultY: CGFloat {
        guard let height = scrollView?.contentSize.height else { return 0.0 }
        return height + spacingFromLastCell
    }

    deinit { activityIndicatorView?.removeFromSuperview() }

    init (scrollView: UIScrollView, spacingFromLastCell: CGFloat, spacingFromLastCellWhenLoadMoreActionStart: CGFloat) {
        self.scrollView = scrollView
        self.spacingFromLastCell = spacingFromLastCell
        self.spacingFromLastCellWhenLoadMoreActionStart = spacingFromLastCellWhenLoadMoreActionStart
        let size:CGFloat = 40
        let frame = CGRect(x: (scrollView.frame.width-size)/2, y: scrollView.contentSize.height + spacingFromLastCell, width: size, height: size)
        let activityIndicatorView = UIActivityIndicatorView(frame: frame)
        if #available(iOS 13.0, *)
        {
            activityIndicatorView.color = .label
        }
        else
        {
            activityIndicatorView.color = .black
        }
        activityIndicatorView.autoresizingMask = [.flexibleLeftMargin, .flexibleRightMargin]
        activityIndicatorView.hidesWhenStopped = true
        scrollView.addSubview(activityIndicatorView)
        self.activityIndicatorView = activityIndicatorView
    }

    private var isHidden: Bool {
        guard let scrollView = scrollView else { return true }
        return scrollView.contentSize.height < scrollView.frame.size.height
    }

    func start(closure: (() -> Void)?) {
        guard let scrollView = scrollView, let activityIndicatorView = activityIndicatorView else { return }
        let offsetY = scrollView.contentOffset.y
        activityIndicatorView.isHidden = isHidden
        if !isHidden && offsetY >= 0 {
            let contentDelta = scrollView.contentSize.height - scrollView.frame.size.height
            let offsetDelta = offsetY - contentDelta
            
            let newY = defaultY-offsetDelta
            if newY < scrollView.frame.height {
                activityIndicatorView.frame.origin.y = newY
            } else {
                if activityIndicatorView.frame.origin.y != defaultY {
                    activityIndicatorView.frame.origin.y = defaultY
                }
            }

            if !activityIndicatorView.isAnimating {
                if offsetY > contentDelta && offsetDelta >= spacingFromLastCellWhenLoadMoreActionStart && !activityIndicatorView.isAnimating {
                    activityIndicatorView.startAnimating()
                    closure?()
                }
            }

            if scrollView.isDecelerating {
                if activityIndicatorView.isAnimating && scrollView.contentInset.bottom == 0 {
                    UIView.animate(withDuration: 0.3) { [weak self] in
                        if let bottom = self?.spacingFromLastCellWhenLoadMoreActionStart {
                            scrollView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: bottom, right: 0)
                        }
                    }
                }
            }
        }
    }

    func stop(completion: (() -> Void)? = nil) {
        guard let scrollView = scrollView , let activityIndicatorView = activityIndicatorView else { return }
        let contentDelta = scrollView.contentSize.height - scrollView.frame.size.height
        let offsetDelta = scrollView.contentOffset.y - contentDelta
        if offsetDelta >= 0 {
            UIView.animate(withDuration: 0.3, animations: {
                scrollView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
            }) { _ in completion?() }
        } else {
            scrollView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
            completion?()
        }
        activityIndicatorView.stopAnimating()
    }
}

用法

初始化

activityIndicator = LoadMoreActivityIndicator(scrollView: tableView, spacingFromLastCell: 10, spacingFromLastCellWhenLoadMoreActionStart: 60)

处理

extension ViewController: UITableViewDelegate {
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        activityIndicator.start {
            DispatchQueue.global(qos: .utility).async {
                sleep(3)
                DispatchQueue.main.async { [weak self] in
                    self?.activityIndicator.stop()
                }
            }
        }
    }
}

完整样本

不要忘记粘贴解决方案代码。

import UIKit

class ViewController: UIViewController {
    
    fileprivate var activityIndicator: LoadMoreActivityIndicator!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        let tableView = UITableView(frame: view.frame)
        view.addSubview(tableView)
        tableView.translatesAutoresizingMaskIntoConstraints = false
        tableView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        tableView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        tableView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
        tableView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
        
        tableView.dataSource = self
        tableView.delegate = self
        tableView.tableFooterView = UIView()
        activityIndicator = LoadMoreActivityIndicator(scrollView: tableView, spacingFromLastCell: 10, spacingFromLastCellWhenLoadMoreActionStart: 60)
    }
}

extension ViewController: UITableViewDataSource {
    
    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 30
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = UITableViewCell()
        cell.textLabel?.text = "\(indexPath)"
        return cell
    }
}

extension ViewController: UITableViewDelegate {
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        activityIndicator.start {
            DispatchQueue.global(qos: .utility).async {
                for i in 0..<3 {
                    print("!!!!!!!!! \(i)")
                    sleep(1)
                }
                DispatchQueue.main.async { [weak self] in
                    self?.activityIndicator.stop()
                }
            }
        }
    }
}

结果

Answer 5

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {
    NSInteger lastSectionIndex = [tableView numberOfSections] - 1;
    NSInteger lastRowIndex = [tableView numberOfRowsInSection:lastSectionIndex] - 1;
    if ((indexPath.section == lastSectionIndex) && (indexPath.row == lastRowIndex)) {
        // This is the last cell
        [self loadMore];
    }
}

如果您使用 Core Data 和 NSFetchedResultsController，那么 loadMore 可能如下所示：

// Load more
- (void)loadMore {
    [self.fetchedResultsController.fetchRequest setFetchLimit:newFetchLimit];
    [NSFetchedResultsController deleteCacheWithName:@"cache name"];
    NSError *error;
    if (![self.fetchedResultsController performFetch:&error]) {
        // Update to handle the error appropriately.
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    }

    [self.tableView reloadData];
}

Answer 6

详情

• Swift 5.1，Xcode 11.3.1

解决方案

Loadmore 的遗传 UITableView 扩展。

在你的新文件中添加这个 UITableView + Extension

extension UITableView {

func indicatorView() -> UIActivityIndicatorView{
    var activityIndicatorView = UIActivityIndicatorView()
    if self.tableFooterView == nil {
        let indicatorFrame = CGRect(x: 0, y: 0, width: self.bounds.width, height: 80)
        activityIndicatorView = UIActivityIndicatorView(frame: indicatorFrame)
        activityIndicatorView.autoresizingMask = [.flexibleLeftMargin, .flexibleRightMargin]
        
        if #available(iOS 13.0, *) {
            activityIndicatorView.style = .large
        } else {
            // Fallback on earlier versions
            activityIndicatorView.style = .whiteLarge
        }
        
        activityIndicatorView.color = .systemPink
        activityIndicatorView.hidesWhenStopped = true

        self.tableFooterView = activityIndicatorView
        return activityIndicatorView
    }
    else {
        return activityIndicatorView
    }
}

func addLoading(_ indexPath:IndexPath, closure: @escaping (() -> Void)){
    indicatorView().startAnimating()
    if let lastVisibleIndexPath = self.indexPathsForVisibleRows?.last {
        if indexPath == lastVisibleIndexPath && indexPath.row == self.numberOfRows(inSection: 0) - 1 {
            DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
                closure()
            }
        }
    }
}

func stopLoading() {
    if self.tableFooterView != nil {
        self.indicatorView().stopAnimating()
        self.tableFooterView = nil
    }
    else {
        self.tableFooterView = nil
    }
} 
}

现在，只需在 UITableViewDelegate Method willDisplay Cell 中添加以下代码行并确保 tableView.delegate = self

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
    // need to pass your indexpath then it showing your indicator at bottom 
    tableView.addLoading(indexPath) {
        // add your code here
        // append Your array and reload your tableview
        tableView.stopLoading() // stop your indicator
    }
}

结果

就是这样..希望这有帮助。谢谢你

Answer 7

我已经实现了我在 stackoverflow 中找到的一种解决方案，它运行良好，但我认为 shinyuX 的解决方案非常容易实现，并且对于我的建议运行良好。 如果有人想要不同的解决方案，可以使用下面的这个。

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{

   // UITableView only moves in one direction, y axis
    CGFloat currentOffset = scrollView.contentOffset.y;
    CGFloat maximumOffset = scrollView.contentSize.height - scrollView.frame.size.height;

    //NSInteger result = maximumOffset - currentOffset;

    // Change 10.0 to adjust the distance from bottom
    if (maximumOffset - currentOffset <= 10.0) {
        [self loadOneMorePage];
        //[self methodThatAddsDataAndReloadsTableView];
    }
}

Answer 8

在您的查询中使用限制和偏移量，并用该内容填充您的表格视图。当用户向下滚动时，加载下一个偏移量。

在您的UITableViewDelegate 中实现tableView:willDisplayCell:forRowAtIndexPath: 方法并检查它是否是最后一行

Answer 9

以下链接将提供示例代码。 #Swift3

用户需要拉起最后一个表格视图单元格，至少 2 个单元格的高度才能从服务器获取更多数据。

您会发现 Process 单元格也显示加载过程，就像在最后一个单元格中一样。

它在 Swift3 中

https://github.com/yogendrabagoriya/YBTableViewPullData

Answer 10

另一个使用选项（Swift 3 和 iOS 10+）：

class DocumentEventsTableViewController: UITableViewController, UITableViewDataSourcePrefetching {

     var currentPage: Int = 1
     let pageSize: Int = 10 // num of items in one page

     override func viewDidLoad() {
         super.viewDidLoad()

         self.tableView.prefetchDataSource = self
     }

     func tableView(_ tableView: UITableView, prefetchRowsAt indexPaths: [IndexPath]) {
         let upcomingRows = indexPaths.map { $0.row }

         if let maxIndex = upcomingRows.max() {

            let nextPage: Int = Int(ceil(Double(maxIndex) / Double(pageSize))) + 1

            if nextPage > currentPage {
                 // Your function, which attempts to load respective page from the local database
                 loadLocalData(page: nextPage)

                 // Your function, which makes a network request to fetch the respective page of data from the network
                 startLoadingDataFromNetwork(page: nextPage) 

                 currentPage = nextPage
             }
         }
     }
 }

对于相当小的页面（约 10 个项目），您可能需要手动为第 1 页和第 2 页添加数据，因为 nextPage 可能在大约 1-2 的某个位置，直到表格有几个项目可以很好地滚动。但它适用于所有后续页面。

Answer 11

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

    if (news.count == 0) {
        return 0;
    } else {
        return news.count +  1 ;
    }
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    @try {

        uint position = (uint) (indexPath.row);
        NSUInteger row = [indexPath row];
        NSUInteger count = [news count];

        //show Load More
        if (row == count) {
            UITableViewCell *cell = nil;

            static NSString *LoadMoreId = @"LoadMore";
            cell = [tableView dequeueReusableCellWithIdentifier:LoadMoreId];
            if (cell == nil) {
                cell = [[UITableViewCell alloc]
                        initWithStyle:UITableViewCellStyleDefault
                      reuseIdentifier:LoadMoreId];
            }
            if (!hasMoreLoad) {
                cell.hidden = true;
            } else {

                cell.textLabel.text = @"Load more items...";
                cell.textLabel.textColor = [UIColor blueColor];
                cell.textLabel.font = [UIFont boldSystemFontOfSize:14];
                NSLog(@"Load more");
                if (!isMoreLoaded) {
                    isMoreLoaded = true;
                    [self performSelector:@selector(loadMoreNews) withObject:nil afterDelay:0.1];
                }
            }

            return cell;

        } else {
            NewsRow *cell = nil;

            NewsObject *newsObject = news[position];
            static NSString *CellIdentifier = @"NewsRow";
            cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

            if (cell == nil) {
                // Load the top-level objects from the custom cell XIB.
                NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:CellIdentifier owner:self options:nil];
                // Grab a pointer to the first object (presumably the custom cell, as that's all the XIB should contain).
                cell = topLevelObjects[0];
                // Configure the cell...

            }

            cell.title.text = newsObject.title;             
            return cell;
        }

    }
    @catch (NSException *exception) {
        NSLog(@"Exception occurred: %@, %@", exception, [exception userInfo]);
    }
    return nil;
}

这篇文章的解释很好。

http://useyourloaf.com/blog/2010/10/02/dynamically-loading-new-rows-into-a-table.html

很简单，您必须添加最后一行并将其隐藏，当表格行到达最后一行时，而不是显示该行并加载更多项目。

Answer 12

你应该检查 ios UITableViewDataSourcePrefetching。

class ViewController: UIViewController {
    @IBOutlet weak var mytableview: UITableView!

    override func viewDidLoad() {
        super.viewDidLoad()
        mytableview.prefetchDataSource = self
    }

 func tableView(_ tableView: UITableView, prefetchRowsAt indexPaths: [IndexPath]) {
        print("prefetchdRowsAtIndexpath \(indexPaths)")
    }

    func tableView(_ tableView: UITableView, cancelPrefetchingForRowsAt indexPaths: [IndexPath]) {
        print("cancelPrefetchingForRowsAtIndexpath \(indexPaths)")
    }


}

• https://developer.apple.com/documentation/uikit/uitableviewdatasourceprefetching https://andreygordeev.com/2017/02/20/uitableview-prefetching/

Answer 13

对于 Xcode 10.1、Swift 4.2

This video 似乎是一个很棒的教程！

启动/完成项目：https://github.com/RobCanton/Swift-Infinite-Scrolling-Example

import UIKit

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

    var tableView:UITableView!

    var fetchingMore = false
    var items = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        initTableView()
    }

    func initTableView() {
        tableView = UITableView(frame: view.bounds, style: .plain)
        tableView.register(UITableViewCell.self, forCellReuseIdentifier: "tableCell")
        tableView.delegate = self
        tableView.dataSource = self

        view.addSubview(tableView)
        tableView.translatesAutoresizingMaskIntoConstraints = false

        let layoutGuide = view.safeAreaLayoutGuide
        tableView.leadingAnchor.constraint(equalTo: layoutGuide.leadingAnchor).isActive = true
        tableView.topAnchor.constraint(equalTo: layoutGuide.topAnchor).isActive = true
        tableView.trailingAnchor.constraint(equalTo: layoutGuide.trailingAnchor).isActive = true
        tableView.bottomAnchor.constraint(equalTo: layoutGuide.bottomAnchor).isActive = true

        tableView.reloadData()
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return items.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
            let cell = tableView.dequeueReusableCell(withIdentifier: "tableCell", for: indexPath)
            cell.textLabel?.text = "Item \(items[indexPath.row])"
            return cell
    }

    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        let offsetY = scrollView.contentOffset.y
        let contentHeight = scrollView.contentSize.height

        if offsetY > contentHeight - scrollView.frame.height * 4 {
            if !fetchingMore {
                beginBatchFetch()
            }
        }
    }

    func beginBatchFetch() {
        fetchingMore = true
        print("Call API here..")
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.50, execute: {
            print("Consider this as API response.")
            let newItems = (self.items.count...self.items.count + 12).map { index in index }
            self.items.append(contentsOf: newItems)
            self.fetchingMore = false
            self.tableView.reloadData()
        })
    }
}

Answer 14

用于从 API 加载，它适用于我，Xcode10，swift 4.2：

1- 创建新的 Swift 文件并这样做：

//
//  apiTVCController.swift
//  ApiTestingTableView
//
//  Created by Hooma7n on 4/7/19.
//  Copyright © 2019 Hooma7n. All rights reserved.
//

import Foundation
import Alamofire

class apiget {

    var tableData : [Datum] = []
    var loadin : [Datum] = []
    var testfortotal : Int?


    func getfromapi(completionHandler : ((_ isSucess : Bool) -> Void)?) {
        let url = "https://reqres.in/api/users?page=1"
        Alamofire.request(url, method: .get, parameters: nil, encoding: JSONEncoding.default, headers: nil)
            .responseJSON(completionHandler : { response in
                switch response.result {
                case .success(let data):
                    guard let jsonData = try? JSONSerialization.data(withJSONObject: data, options: JSONSerialization.WritingOptions.prettyPrinted) else {return}
                    let decoder = JSONDecoder()
                    guard let result = try? decoder.decode(Welcome.self, from: jsonData) else {return}
                    self.tableData = result.data ?? []
                    self.testfortotal = result.total ?? 0
                    completionHandler?(true)

                //                    print(result)
                case .failure(let error):
                    print(error)
                }
            })
    }

    var pagecounter : Int = 2


    func loadmore(completionHandler : ((_ isSucess : Bool) -> Void)?){

        let url = "https://reqres.in/api/users?page=\(pagecounter)"
        Alamofire.request(url, method: .get, parameters: nil, encoding: JSONEncoding.default, headers: nil)
            .responseJSON(completionHandler : { response in
                switch response.result {
                case .success(let data):
                    guard let jsonData = try? JSONSerialization.data(withJSONObject: data, options: JSONSerialization.WritingOptions.prettyPrinted) else {return}
                    let decoder = JSONDecoder()
                    guard let myresult = try? decoder.decode(Welcome.self, from: jsonData) else {return}
                    self.loadin = myresult.data ?? []
                    self.tableData.append(contentsOf: myresult.data ?? [])
                    completionHandler?(true)
                    print(self.pagecounter)
                    self.pagecounter += 1

                //                    print(myresult)
                case .failure(let error):
                    print(error)
                }
            })

    }

}

extension apiget {

    struct Welcome: Codable {
        let page, perPage, total, totalPages: Int?
        var data: [Datum]?

        enum CodingKeys: String, CodingKey {
            case page
            case perPage = "per_page"
            case total
            case totalPages = "total_pages"
            case data
        }
    }

    struct Datum: Codable {
        let id: Int?
        let firstName, lastName: String?
        let avatar: String?

        enum CodingKeys: String, CodingKey {
            case id
            case firstName = "first_name"
            case lastName = "last_name"
            case avatar
        }
    }


}

2- 在您的 ViewController 文件（tableView 控制器）中：

//
//  apiTVC.swift
//  ApiTestingTableView
//
//  Created by Hooma7n on 4/7/19.
//  Copyright © 2019 Hooma7n. All rights reserved.
//

import UIKit
import Alamofire

class apiTVC: UITableViewController {

    var datamodel = apiget()

    override func viewDidLoad() {
        super.viewDidLoad()

        datamodel.getfromapi(completionHandler: {finish in
            if finish {self.tableView.reloadData()
            }

        })

    }


    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return datamodel.tableData.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! apiTableViewCell
        cell.firstNameLabel.text = datamodel.tableData[indexPath.row].firstName
        cell.lastNameLabel.text = datamodel.tableData[indexPath.row].lastName
        cell.dateLabel.text = "\(datamodel.tableData[indexPath.row].id ?? 0)"
        cell.profileImageView.loadImage(fromURL: datamodel.tableData[indexPath.row].avatar ?? "")

        return cell

    }

    override func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
        let lastElement = datamodel.tableData.count - 1
        let total = datamodel.testfortotal ?? 12
        if indexPath.row == lastElement && datamodel.tableData.count < total{

            datamodel.loadmore(completionHandler: {finish in
                if finish {

                    self.tableView.reloadData()

                }})
        }
    }
}

如果在你的 viewController 中使用 tableView 设置 delegate,datasource self in viewDidLoad.

Answer 15

只想分享这种方法：

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    NSLog(@"%@", [[YourTableView indexPathsForVisibleRows] lastObject]);
    [self estimatedTotalData];
}

- (void)estimatedTotalData
{
    long currentRow = ((NSIndexPath *)[[YourTableView indexPathsForVisibleRows] lastObject]).row;

    long estimateDataCount = 25;

    while (currentRow > estimateDataCount)
    {
        estimateDataCount+=25;
    }

    dataLimit = estimateDataCount;

    if (dataLimit == currentRow+1)
    {
        dataLimit+=25;
    }

    NSLog(@"dataLimit :%ld", dataLimit);

    [self requestForData];

    // this answers the question..
    //
    if(YourDataSource.count-1 == currentRow)
    {
        NSLog(@"LAST ROW"); //loadMore data
    }
}

NSLog(...); 输出类似于：

<NSIndexPath: 0xc0000000002e0016> {length = 2, path = 0 - 92}
dataLimit :100
<NSIndexPath: 0xc000000000298016> {length = 2, path = 0 - 83}
dataLimit :100
<NSIndexPath: 0xc000000000278016> {length = 2, path = 0 - 79}
dataLimit :100
<NSIndexPath: 0xc000000000238016> {length = 2, path = 0 - 71}
dataLimit :75
<NSIndexPath: 0xc0000000001d8016> {length = 2, path = 0 - 59}
dataLimit :75
<NSIndexPath: 0xc0000000001c0016> {length = 2, path = 0 - 56}
dataLimit :75
<NSIndexPath: 0xc000000000138016> {length = 2, path = 0 - 39}
dataLimit :50
<NSIndexPath: 0xc000000000120016> {length = 2, path = 0 - 36}
dataLimit :50
<NSIndexPath: 0xc000000000008016> {length = 2, path = 0 - 1}
dataLimit :25
<NSIndexPath: 0xc000000000008016> {length = 2, path = 0 - 1}
dataLimit :25

这对于显示本地存储的数据很有用。 最初我将 dataLimit 声明为 25，这意味着 uitableview 将有 0-24（最初）。

如果用户滚动到底部并且最后一个单元格可见，dataLimit 将添加 25...

注意：这更像是一个 UITableView 数据分页，:)

Answer 16

-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {

NSInteger sectionsAmount = [tableView numberOfSections];
NSInteger rowsAmount = [tableView numberOfRowsInSection:[indexPath section]];
if ([indexPath section] == sectionsAmount - 1 && [indexPath row] == rowsAmount - 1) {
    //get last row
    if (!isSearchActive && !isFilterSearchActive) {
        if (totalRecords % 8 == 0) {
            int64_t delayInSeconds = 2.0;
            dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
            dispatch_after(popTime, dispatch_get_main_queue(), ^(void) {


            [yourTableView beginUpdates];
            [yourTableView insertRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationAutomatic];
            [yourTableView endUpdates];
            });
        }
    }
}
}

Answer 17

解决此问题的最佳方法是在表格底部添加单元格，该单元格将包含指示器。

在swift中你需要添加这个：

1. 创建 cellLoading 类型的新单元格，这将保存指标。看下面的代码
2. 查看行数并加1（这是用于加载单元格）。
3. 如果 idexPath.row == yourArray.count 则需要检查 rawAtIndex，然后返回加载单元格。

看看下面的代码：

import UIKit

class LoadingCell: UITableViewCell {

@IBOutlet weak var indicator: UIActivityIndicatorView!


}

对于表格视图： numOfRows：

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return  yourArray.count + 1
}

cellForRawAt 索引路径：

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    if indexPath.row == users.count  {
        // need to change
        let loading = Bundle.main.loadNibNamed("LoadingCell", owner: LoadingCell.self , options: nil)?.first as! LoadingCell
        return loading

    }

    let yourCell = tableView.dequeueReusableCell(withIdentifier: "cellCustomizing", for: indexPath) as! UITableViewCell

    return yourCell

}

如果您注意到我的加载单元是从 nib 文件创建的。 This videos 会解释我做了什么。

Answer 18

let threshold = 100.0 // threshold from bottom of tableView
var isLoadingMore = false // flag


func scrollViewDidScroll(scrollView: UIScrollView) {
    let contentOffset = scrollView.contentOffset.y
    let maximumOffset = scrollView.contentSize.height - scrollView.frame.size.height;

    if !isLoadingMore && (maximumOffset - contentOffset <= threshold) {
        // Get more data - API call
        self.isLoadingMore = true

        // Update UI
        dispatch_async(dispatch_get_main_queue()) {
            tableView.reloadData()
            self.isLoadingMore = false
        }
    }
  }

Answer 19

这是示例代码。

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell:ShowComplainCell = tableView.dequeueReusableCell(withIdentifier: "cell")! as! ShowComplainCell

    let item  = self.dataArray[indexPath.row] as! ComplainListItem;

    let indexPathArray = NSArray(array: tableView.indexPathsForVisibleRows!)
    let vIndexPath = indexPathArray.lastObject as! NSIndexPath

    let lastItemReached = item.isEqual(self.dataArray.lastObject);

    if (lastItemReached && vIndexPath.row == (self.dataArray.count - 1))
       {

        self.loadData()
       }
    


    return cell
    
}

indexPathArray: 是可见的行。

vIndexPath:最后一个索引路径可见

加载数据

 func loadData(){

       if(isReloadTable){
       let HUD = MBProgressHUD.showAdded(to: self.view, animated: true)
       let manager :AFHTTPSessionManager = AFHTTPSessionManager()
     
       
           var param = NSDictionary()
           param = [
               "category":cat_id,
               "smart_user_id": USERDEF.value(forKey: "user_id") as! String,
               "page":page,
               "phone":phone! as String
               
           ] as [String : Any] as NSDictionary
           print("param1 = \(param)")

           manager.get("lists.php?", parameters: param, progress: nil, success: { (task:URLSessionDataTask, responseObject: Any) in
               
     
                       let adsArray =  dic["results"] as! NSArray;
                       for item in adsArray {
                           let item  = ComplainListItem(dictionary: item as! NSDictionary )
                           self.dataArray.add(item)
                       }
                   
                       self.view.addSubview(self.cityTableView)
                       self.cityTableView.reloadData()
                   
                   if(adsArray.count==10){
                       self.cityTableView.reloadData()
                       self.isReloadTable = true
                       self.page+=1
                   }else if(adsArray.count<10){
                       self.cityTableView.reloadData()
                       self.isReloadTable = false
               }
               
               HUD.hide(animated:true)
               
           }) { (operation,error) -> Void in
               print("error = \(error)")
               HUD.hide(animated:true)
           }
       }
        
   }

检查您的 dataArray 计数，即 myadsarray 检查是否等于您的数据限制。然后如果dataArray count等于下一页，如果不等于小于10，则调用所有数据。