示意图：

 封装代码备个份

import SwiftUIlet ScreenH = UIScreen.main.bounds.height/// 状态栏高度。非刘海屏20，X是44，11是48，12之后是47
let kStatusBarHeight = STATUSBAR_HEIGHT()
let kBottomSafeHeight = INDICATOR_HEIGHT()/// 导航条高度
let kContentNavBarHeight = 44.0
let kNavHeight = (kStatusBarHeight + kContentNavBarHeight)
let kTabBarHeight = (49.0 + kBottomSafeHeight)/// 状态栏高度。X是44，其他是20
func STATUSBAR_HEIGHT() ->CGFloat {if #available(iOS 13.0, *) {return getWindow()?.windowScene?.statusBarManager?.statusBarFrame.height ?? 0} else {return UIApplication.shared.statusBarFrame.height}
}/// 底部指示条高度
func INDICATOR_HEIGHT() ->CGFloat {if #available(iOS 11.0, *) {return getWindow()?.safeAreaInsets.bottom ?? 0} else {return 0}
}/// 获取当前设备window用于判断尺寸
func getWindow() -> UIWindow? {if #available(iOS 13.0, *) {let winScene = UIApplication.shared.connectedScenes.first as? UIWindowScenereturn winScene?.windows.first} else {return UIApplication.shared.keyWindow}
}struct RefreshScrollView: View {@State private var preOffset: CGFloat = 0@State private var offset: CGFloat = 0@State private var frozen = false@State private var rotation: Angle = .degrees(0)@State private var updateTime: Date = Date()var offDown : CGFloat = 0.0 // 滑动内容总高var listH : CGFloat = 0.0 // 列表高度var threshold: CGFloat = 70@Binding var isRefreshing: Bool // 下拉刷新@Binding var isMore: Bool // 加载更多let content: Content// 下拉刷新出发回调var refreshTrigger: (() -> Void)?// 上拉加载更多var moreTrigger: (() -> Void)?init(_ threshold: CGFloat = 70, offDown: CGFloat, listH: CGFloat, refreshing: Binding, isMore: Binding, refreshTrigger: @escaping () -> Void, moreTrigger: @escaping () -> Void, @ViewBuilder content: () -> Content) {self.threshold = thresholdself._isRefreshing = refreshingself.content = content()self.refreshTrigger = refreshTriggerself.moreTrigger = moreTriggerself._isMore = isMoreself.offDown = offDownself.listH = listH}var body: some View {VStack {ScrollView {ZStack(alignment: .top) {MovingPositionView()VStack {self.content.alignmentGuide(.top, computeValue: { _ in(self.isRefreshing && self.frozen) ? -self.threshold : 0})}RefreshHeader(height: self.threshold,loading: self.isRefreshing,frozen: self.frozen,rotation: self.rotation,updateTime: self.updateTime)}if isMore{RefreshMore(height: self.threshold, rotation: self.rotation).onAppear(){if nil != moreTrigger{moreTrigger!()}}}}.background(FixedPositionView()).onPreferenceChange(RefreshPreferenceTypes.RefreshPreferenceKey.self) { values inself.calculate(values)}.onChange(of: isRefreshing) { refreshing inDispatchQueue.main.async {if !refreshing {self.updateTime = Date()}}}}}func calculate(_ values: [RefreshPreferenceTypes.RefreshPreferenceData]) {DispatchQueue.main.async {/// 计算croll offsetlet movingBounds = values.first(where: { $0.viewType == .movingPositionView })?.bounds ?? .zerolet fixedBounds = values.first(where: { $0.viewType == .fixedPositionView })?.bounds ?? .zeroself.offset = movingBounds.minY - fixedBounds.minYself.rotation = self.headerRotation(self.offset)/// 触发刷新if !self.isRefreshing, self.offset > self.threshold, self.preOffset <= self.threshold {self.isRefreshing = trueif nil != refreshTrigger{refreshTrigger!()}}if self.isRefreshing {if self.preOffset > self.threshold, self.offset <= self.threshold {self.frozen = true}} else {self.frozen = false}self.preOffset = self.offset//加载更多触发条件print(offDown + threshold, -(self.preOffset - listH))if (offDown + threshold <= -(self.preOffset - listH)) && offDown > 0 {isMore = true}}}func headerRotation(_ scrollOffset: CGFloat) -> Angle {if scrollOffset < self.threshold * 0.60 {return .degrees(0)} else {let h = Double(self.threshold)let d = Double(scrollOffset)let v = max(min(d - (h * 0.6), h * 0.4), 0)return .degrees(180 * v / (h * 0.4))}}//     位置固定不变的viewstruct FixedPositionView: View {var body: some View {GeometryReader { proxy inColor.clear.preference(key: RefreshPreferenceTypes.RefreshPreferenceKey.self,value: [RefreshPreferenceTypes.RefreshPreferenceData(viewType: .fixedPositionView, bounds: proxy.frame(in: .global))])}}}//     位置随着滑动变化的view，高度为0struct MovingPositionView: View {var body: some View {GeometryReader { proxy inColor.clear.preference(key: RefreshPreferenceTypes.RefreshPreferenceKey.self,value: [RefreshPreferenceTypes.RefreshPreferenceData(viewType: .movingPositionView, bounds: proxy.frame(in: .global))])}.frame(height: 0)}}
}//MARK: - 下拉刷新UI
struct RefreshHeader: View {var height: CGFloatvar loading: Boolvar frozen: Boolvar rotation: Anglevar updateTime: Datelet dateFormatter: DateFormatter = {let df = DateFormatter()df.dateFormat = "MM月dd日 HH时mm分ss秒"return df}()var body: some View {HStack(spacing: 20) {Spacer()Group {if self.loading {VStack {Spacer()ActivityRep()Spacer()}} else {Image(systemName: "arrow.down").resizable().aspectRatio(contentMode: .fit).rotationEffect(rotation)}}.frame(width: height * 0.25, height: height * 0.8).fixedSize().offset(y: (loading && frozen) ? 0 : -height)VStack(spacing: 5) {Text("\(self.loading ? "正在刷新数据" : "下拉刷新数据")").foregroundColor(.secondary).font(.subheadline)Text("\(self.dateFormatter.string(from: updateTime))").foregroundColor(.secondary).font(.subheadline)}.offset(y: -height + (loading && frozen ? +height : 0.0))Spacer()}.frame(height: height)}
}//MARK: - 加载更多UI
struct RefreshMore: View{var height: CGFloatvar rotation: Anglevar body: some View{HStack(spacing: 20) {Spacer()Group {VStack {Spacer()ActivityRep()Spacer()}}.frame(width: height * 0.25, height: height * 0.8).fixedSize()VStack() {Text("正在加载更多数据").foregroundColor(.secondary).font(.subheadline)}Spacer()}.frame(height: height)}
}struct RefreshPreferenceTypes {enum ViewType: Int {case fixedPositionViewcase movingPositionView}struct RefreshPreferenceData: Equatable {let viewType: ViewTypelet bounds: CGRect}struct RefreshPreferenceKey: PreferenceKey {static var defaultValue: [RefreshPreferenceData] = []static func reduce(value: inout [RefreshPreferenceData],nextValue: () -> [RefreshPreferenceData]) {value.append(contentsOf: nextValue())}}
}struct ActivityRep: UIViewRepresentable {func makeUIView(context: UIViewRepresentableContext) -> UIActivityIndicatorView {return UIActivityIndicatorView()}func updateUIView(_ uiView: UIActivityIndicatorView, context: UIViewRepresentableContext) {uiView.startAnimating()}
}

二、Refresh

用现成的工具就很香了

https://github.com/wxxsw/Refresh

• 支持下拉刷新和滚动装载更多。
• 完全基于SwiftUI，没有UIViewRepresentable，没有UIViewControllerRepresentable。
• 兼容NavigationView,TabView。
• 完全自定义用户界面。

使用：

import SwiftUIstruct MPPhotographView: View {@State var isRefresh = false@State var isMore = false@State private var noMore: Bool = false@State var dataArr: [[String: String]] = []@State var page: Int = 1private let pageSize: Int = 20var body: some View {ScrollView {RefreshHeader(refreshing: $isRefresh, action: {pullRefreshData()}) { progress inif self.isRefresh {Text("refreshing...")} else {Text("Pull to refresh")}}ForEach(0..

import SwiftUIstruct MPAlbumView: View {@State var dataArr: [[String: String]] = []var body: some View {RefreshableScrollView { done inpullRefreshData(done)} progress: { state inRefreshActivityIndicator(isAnimating: state == .loading) {$0.hidesWhenStopped = false}} content: {VStack {ForEach(0..

import SwiftUIstruct MPAlbumView: View {@State var dataArr: [[String: String]] = []var body: some View {VStack {ForEach(0..