直播平台源码，自定义下拉刷新控件

import Foundation<br>import UIKit<br>import SnapKit<br>class XRefreshControl: UIRefreshControl {<br>    var observation: NSKeyValueObservation?<br>    var isLocalRefreshing: Bool = false<br>    let indicator = UIProgressView(progressViewStyle: .bar)<br>    var refreshingBlock: (()->Void)?<br>    <br>    override init(frame: CGRect) {<br>        super.init(frame: frame)<br>        <br>        observation = observe(<br>            \.frame,<br>             options: .new<br>        ) { [weak self] object, change in<br>            if self?.isRefreshing == true {<br>                if self?.isLocalRefreshing == false {<br>                    if self?.refreshingBlock != nil {<br>                        self?.refreshingBlock!()<br>                    }<br>                }<br>                self?.isLocalRefreshing = true<br>            } else {<br>                let height = change.newValue!.height<br>                self?.indicator.progress = min(Float(abs(height / 60)), 1)<br>            }<br>        }<br>    }<br>    convenience init(refreshingBlock: @escaping ()->Void) {<br>        self.init(frame: .zero)<br>        <br>        self.refreshingBlock = refreshingBlock<br>        <br>        self.layer.masksToBounds = true<br>        self.backgroundColor = .red<br>        <br>        let v = UIView()<br>        v.backgroundColor = .red<br>        <br>        let center = UIView()<br>        v.addSubview(center)<br>        <br>        let title = UILabel()<br>        title.text = "加载中"<br>        title.textColor = .black<br>        center.addSubview(title)<br>        <br>        indicator.layer.masksToBounds = true<br>        center.addSubview(indicator)<br>        <br>        self.addSubview(v)<br>        v.snp.makeConstraints { make in<br>            make.edges.equalToSuperview()<br>        }<br>        center.snp.makeConstraints { make in<br>            make.center.equalToSuperview()<br>            make.width.equalToSuperview()<br>        }<br>        indicator.snp.makeConstraints { make in<br>            make.top.equalToSuperview()<br>            make.width.height.equalTo(32)<br>            make.centerX.equalToSuperview()<br>        }<br>        title.snp.makeConstraints { make in<br>            make.top.equalTo(indicator.snp.bottom)<br>            make.bottom.equalToSuperview()<br>            make.centerX.equalToSuperview()<br>        }<br>    }<br>    <br>    required init?(coder: NSCoder) {<br>        fatalError("init(coder:) has not been implemented")<br>    }<br>    <br>    deinit {<br>        observation = nil<br>    }<br>    <br>    override func endRefreshing() {<br>        super.endRefreshing()<br>        <br>        self.isLocalRefreshing = false<br>        indicator.progress = 0<br>    }<br>}<br>extension UITableView {<br>    func endRefreshing() {<br>        if ((self.refreshControl?.isKind(of: XRefreshControl.self)) != nil) {<br>            self.refreshControl?.endRefreshing()<br>        }<br>    }<br>}