iPhone像Tweetie一样下拉刷新

iPhone像Tweetie一样下拉刷新的实现方法

swift
import UIKit
class RefreshViewController: UIViewController {
    // 刷新视图
    private var refreshView: RefreshView!
    override func viewDidLoad() {
        super.viewDidLoad()
        // 初始化刷新视图
        refreshView = RefreshView(frame: CGRect(x: 0, y: -100, width: view.bounds.width, height: 100))
        refreshView.backgroundColor = .white
        view.addSubview(refreshView)
        // 添加下拉手势识别器
        let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(handlePanGesture(_:)))
        view.addGestureRecognizer(panGestureRecognizer)
    }
    @objc func handlePanGesture(_ gestureRecognizer: UIPanGestureRecognizer) {
        let translation = gestureRecognizer.translation(in: view)
        if translation.y > 0 && gestureRecognizer.state == .changed {
            // 用户正在下拉页面
            refreshView.updateProgress(translation.y)
        } else if gestureRecognizer.state == .ended {
            // 用户完成下拉动作
            if translation.y >= 100 {
                // 达到刷新阈值，执行刷新操作
                refreshView.startRefreshing()
                performRefresh()
            } else {
                // 未达到刷新阈值，恢复原始状态
                refreshView.reset()
            }
        }
    }
    func performRefresh() {
        // 执行刷新操作
        DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
            // 模拟刷新完成
            self.refreshView.endRefreshing()
        }
    }
}
class RefreshView: UIView {
    private var progressView: UIProgressView!
    override init(frame: CGRect) {
        super.init(frame: frame)
        // 初始化进度条视图
        progressView = UIProgressView(progressViewStyle: .default)
        progressView.frame = CGRect(x: 0, y: frame.height - 2, width: frame.width, height: 2)
        addSubview(progressView)
    }
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    func updateProgress(_ offsetY: CGFloat) {
        let progress = min(1.0, max(0.0, offsetY / 100.0))
        progressView.setProgress(Float(progress), animated: false)
    }
    func startRefreshing() {
        progressView.isHidden = true
        let activityIndicator = UIActivityIndicatorView(style: .gray)
        activityIndicator.center = CGPoint(x: frame.width / 2, y: frame.height / 2)
        activityIndicator.startAnimating()
        addSubview(activityIndicator)
    }
    func endRefreshing() {
        progressView.progress = 0.0
        progressView.isHidden = false
        removeFromSuperview()
    }
    func reset() {
        progressView.progress = 0.0
    }
}