Refresh for Swift

概述//// RefreshControl.swift// //// Created by Long on 16/09/14.// Copyright © 2016年 Apple. All rights reserved.//import UIKit// 自定义下拉刷新的状态private enum RefreshType: Int { // 下拉刷新状态

////  RefreshControl.swift//  ////  Created by Long on 16/09/14.//  copyright © 2016年 Apple. All rights reserved.//import UIKit//  自定义下拉刷新的状态private enum RefreshType: Int {    //  下拉刷新状态    case normal = 0    //  松手就刷新    case pulling = 1    //  正在刷新    case refreshing = 2}//  自定义控件的高度private let RefreshControlHeight: CGfloat = 50//  自定义下拉刷新控件class RefreshControl: UIControl {    //  记录当前刷新的控件    private var currentScrollVIEw: UIScrollVIEw?    //  记录当前刷新状态    private var myRefreshType: RefreshType = .normal {        dIDSet {            switch myRefreshType {            case .normal:                print("下拉刷新")                //  箭头重置,箭头显示,关闭风火轮,内容改成下拉刷新                pullDownImageVIEw.isHIDden = false                UIVIEw.animate(withDuration: 0.25,animations: {                    //  重置箭头位置                    self.pullDownImageVIEw.transform = CGAffinetransform.IDentity                })                indicatorVIEw.stopAnimating()                messageLabel.text = "下拉刷新"                                //  判断上一次刷新状态是正在属性,让重置默认位置                //  oldValue 表示上一次存储的值                if oldValue == .refreshing {                    UIVIEw.animate(withDuration: 0.25,animations: {                        //  设置停留位置,核心代码,重置停留位置                        self.currentScrollVIEw?.contentInset.top -= RefreshControlHeight                    })                }                                                           case .pulling:                print("松手就刷新")                //  箭头调转,内容修改成松手就刷新                UIVIEw.animate(withDuration: 0.25,animations: {                    //  调转箭头位置                    self.pullDownImageVIEw.transform = CGAffinetransform(rotationAngle: CGfloat(M_PI))                })                messageLabel.text = "松手就刷新"                                            case .refreshing:                print("正在刷新")                //  箭头隐藏,开启风火轮,内容改成正在刷新                pullDownImageVIEw.isHIDden = true                //  开启风火轮                indicatorVIEw.startAnimating()                messageLabel.text = "正在刷新..."                                UIVIEw.animate(withDuration: 0.25,animations: {                     //  设置停留位置,核心代码                    self.currentScrollVIEw?.contentInset.top += RefreshControlHeight                })                                //  通知外界刷新数据 (核心代码)                sendActions(for: .valueChanged)                                                                                            }        }    }        // MARK: - 懒加载控件    //  下拉箭头图片    fileprivate lazy var pullDownImageVIEw: UIImageVIEw = UIImageVIEw(image: UIImage(named: "tablevIEw_pull_refresh"))    //  下拉刷新内容 label    fileprivate lazy var messageLabel: UILabel = {        let label = UILabel()        label.text = "下拉刷新"        label.Font = UIFont.systemFont(ofSize: 11)        label.textcolor = UIcolor.gray        return label        }()    //  风火轮    fileprivate lazy var indicatorVIEw: UIActivityIndicatorVIEw = UIActivityIndicatorVIEw(activityIndicatorStyle: .gray)            overrIDe init(frame: CGRect) {        super.init(frame: frame)        //  获取屏幕的宽度        let screenWIDth = UIScreen.main.bounds.size.wIDth        //  设置 frame        self.frame = CGRect(x: 0,y: -RefreshControlHeight,wIDth: screenWIDth,height: RefreshControlHeight)        setupUI()    }        required init?(coder aDecoder: NSCoder) {        fatalError("init(coder:) has not been implemented")    }        //  添加控件设置约束    private func setupUI() {        backgroundcolor = UIcolor.red        //  添加子控件设置约束        addSubvIEw(pullDownImageVIEw)        addSubvIEw(messageLabel)        addSubvIEw(indicatorVIEw)                        //  使用系统布局 autolayout 需要关闭 autoresizing        pullDownImageVIEw.translatesautoresizingMaskIntoConstraints = false        messageLabel.translatesautoresizingMaskIntoConstraints = false        indicatorVIEw.translatesautoresizingMaskIntoConstraints = false                //  添加约束        addConstraint(NSLayoutConstraint(item: pullDownImageVIEw,attribute: .centerX,relatedBy: .equal,toItem: self,multiplIEr: 1,constant: -35))        addConstraint(NSLayoutConstraint(item: pullDownImageVIEw,attribute: .centerY,constant: 0))                addConstraint(NSLayoutConstraint(item: messageLabel,attribute: .leading,toItem: pullDownImageVIEw,attribute: .trailing,constant: 0))        addConstraint(NSLayoutConstraint(item: indicatorVIEw,constant: 0))                addConstraint(NSLayoutConstraint(item: indicatorVIEw,constant: 0))                                           }        //  获取父控件,当前控件将要添加到那个父视图上面    overrIDe func willMove(toSupervIEw newSupervIEw: UIVIEw?) {        print(newSupervIEw)        //  判断是否是可以滚动的控件        if let scrollVIEw = newSupervIEw as? UIScrollVIEw {            //  表示是 UIScrollVIEw 的子类,可以监听器滚动            //  可以使用 kvo 监听 contentOffSet 值得改变                        //  [.new,.old] 表示可以监听新值和旧值得改变            scrollVIEw.addobserver(self,forKeyPath: "contentOffset",options: .new,context: nil)            //  记录刷新视图控件            currentScrollVIEw = scrollVIEw                    }                                    }        //  kvo监听方法    overrIDe func observeValue(forKeyPath keyPath: String?,of object: Any?,change: [NSkeyvalueChangeKey : Any]?,context: UnsafeMutableRawPointer?) {                guard let scrollVIEw = currentScrollVIEw else {            return        }                //  代码执行到此,表示 scrollVIEw 不为 nil                //  计算临界点        let maxY = -(scrollVIEw.contentInset.top + RefreshControlHeight)        //  获取 y 轴偏移量        let contentOffSetY = scrollVIEw.contentOffset.y                       //  判断是否拖动        //  拖动情况下只有两种状态 .normal,pulling        if scrollVIEw.isDragging {            //  表示在拖动 判断的核心            if contentOffSetY < maxY && myRefreshType == .normal  {                myRefreshType = .pulling                print("pulling")            } else if contentOffSetY >= maxY && myRefreshType == .pulling {                myRefreshType = .normal                print("normal")            }                                                        } else {            //  表示松手,只有 pulling 状态 才能进入正在刷新                        if myRefreshType == .pulling {                myRefreshType = .refreshing                print("正在刷新")            }                                            }                            }        //  结束刷新    func endRefreshing() {        myRefreshType = .normal    }        deinit {        //  移除 kvo        currentScrollVIEw?.removeObserver(self,forKeyPath: "contentOffset")    }    }

使用

    //  自定义下拉刷新控件    fileprivate lazy var refreshControl: RefreshControl = RefreshControl()   tableVIEw.addSubvIEw(refreshControl) refreshControl.addTarget(self,action: #selector(更新数据的方法名),for: UIControlEvents.valueChanged)

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