Swift - 表格tableView上拉加载新数据的功能实现（附样例）

import UIKit

class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
    
    //表格视图
    @IBOutlet weak var tableView: UITableView!
    
    //数据集合
    var dataArray = [String]()
    
    //表格底部用来提示数据加载的视图
    var loadMoreView:UIView?
    
    //计数器（用来做延时模拟网络加载效果）
    var timer: Timer!
    
    //用了记录当前是否允许加载新数据（正则加载的时候会将其设为false，放置重复加载）
    var loadMoreEnable = true
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.tableView.delegate = self
        self.tableView.dataSource = self
        
        //上拉刷新
        self.setupInfiniteScrollingView()
        self.tableView.tableFooterView = self.loadMoreView
        
        //首次加载数据
        loadMore()
    }
    
    //上拉刷新视图
    private func setupInfiniteScrollingView() {
        self.loadMoreView = UIView(frame: CGRect(x:0, y:self.tableView.contentSize.height,
                                                 width:self.tableView.bounds.size.width, height:60))
        self.loadMoreView!.autoresizingMask = UIViewAutoresizing.flexibleWidth
        self.loadMoreView!.backgroundColor = UIColor.orange
        
        //添加中间的环形进度条
        let activityViewIndicator = UIActivityIndicatorView(activityIndicatorStyle: .white)
        activityViewIndicator.color = UIColor.darkGray
        let indicatorX = self.view.frame.width/2-activityViewIndicator.frame.width/2
        let indicatorY = self.loadMoreView!.frame.size.height/2-activityViewIndicator.frame.height/2
        activityViewIndicator.frame = CGRect(x:indicatorX, y:indicatorY,
                                             width:activityViewIndicator.frame.width,
                                             height:activityViewIndicator.frame.height)
        activityViewIndicator.startAnimating()
        self.loadMoreView!.addSubview(activityViewIndicator)
    }
    
    // 返回记录数
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return dataArray.count;
    }
    
    //单元格数据设置
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath)
        -> UITableViewCell {
            //设置单元格数据
            let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
            cell.textLabel?.text = self.dataArray[indexPath.row]
            
            //当下拉到底部，执行loadMore()
            if (loadMoreEnable && indexPath.row == self.dataArray.count-1) {
                loadMore()
            }
            
            return cell
    }
    
    //加载更多数据
    func loadMore(){
        print("加载新数据！")
        loadMoreEnable = false
        timer = Timer.scheduledTimer(timeInterval: 2.0, target: self,
                selector: #selector(ViewController.timeOut), userInfo: nil, repeats: true)
    }
    
    //计时器时间到
    @objc func timeOut() {
        let start = self.dataArray.count + 1
        //随机添加10条新数据（时间是当前时间）
        for i in start..<start+20 {
            self.dataArray.append("新闻标题\(i)")
        }
        self.tableView.reloadData()
        loadMoreEnable = true
        
        timer.invalidate()
        timer = nil
    }
}