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LKRefreshView是纯SwiftUI自定义的下拉刷新，上拉加载更多列表刷新控件，支持ScrollView列表快速对接
1.获取ScrollView的内容高度； 2.计算滑动偏移offsetY值与刷新事件的阈值对比回调刷新触发事件； 3.自定义滑动时的header、footer显示内容效果。
//
// LKChildSizeReader.swift
// ZgwBosssCockpit
//
// Created by 李棒棒 on 2023/12/20.
//
import SwiftUI
struct LKChildSizeReader<Content: View>: View {
@Binding var size:CGSize
let content:()->Content
var body: some View {
ZStack {
content()
.background(
GeometryReader { proxy in
Color.clear
.preference(key: LKSizePreferenceKey.self, value: proxy.size)
}
)
}
.onPreferenceChange(LKSizePreferenceKey.self) { preferences in
self.size = preferences
}
}
}
//计算内容size
private struct LKSizePreferenceKey: PreferenceKey {
typealias Value = CGSize
static var defaultValue: Value = .zero
static func reduce(value _: inout Value, nextValue: () -> Value) {
_ = nextValue()
}
}
//计算滑动偏移量
struct LKScrollOffsetPreferenceKey: PreferenceKey {
static var defaultValue = CGFloat.zero
static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) {
value = -(value + nextValue())
}
}
有两种方案： 第一种：使用第一步中的LKScrollOffsetPreferenceKey来获取滑动时的偏移量； 第二种：通过计算LKMovingPositionView和LKFixedPositionView两者之间的y的差，得到offset；
** 1.LKFixedPositionView的代码**
通过.preference为其绑定了一个LKRefreshPreferenceData类型的数据，最重要的目的是保存该view的bounds
import SwiftUI
//固定位置view
struct LKFixedPositionView: View {
var body: some View {
GeometryReader { proxy in
Color.clear
.preference(key: LKRefreshPreferenceType.LKRefreshPreferenceKey.self,
value: [LKRefreshPreferenceType.LKRefreshPreferenceData(viewType: .fixedPositionView, bounds: proxy.frame(in: .global))])
}
}
}
** 2.LKMovingPositionView的代码 **
/// 位置随着滑动变化的view，高度为0
struct LKMovingPositionView: View {
var body: some View {
GeometryReader { proxy in
Color.clear
.preference(key: LKRefreshPreferenceType.LKRefreshPreferenceKey.self, value: [LKRefreshPreferenceType.LKRefreshPreferenceData(viewType: .movingPositionView, bounds: proxy.frame(in: .global))])
}.frame(height:0.0)
}
}
这两个view对用户来说都是不可见的，一个作为背景，另一个放到ScrollView内容的最上边 ** 3.计算offset **
extension LKRefreshView {
func calculate(_ values: [LKRefreshPreferenceType.LKRefreshPreferenceData]) {
DispatchQueue.main.async {
/// 计算sroll offset
let movingBounds = values.first(where: { $0.viewType == .movingPositionView })?.bounds ?? .zero
let fixedBounds = values.first(where: { $0.viewType == .fixedPositionView })?.bounds ?? .zero
self.offset = movingBounds.minY - fixedBounds.minY
if (self.offset >= 0.0) {//下拉
self.headerRotation = self.headerRotation(self.offset)
} else {//上拽
self.footerRotation = self.footerRotation(self.offset)
}
/// 触发刷新
if self.headerRefreshing == false ,
self.offset > self.threshold ,
self.preOffset <= self.threshold {
self.footerRefreshing = false
self.footerFrozen = false
self.headerRefreshing = true
if refreshTrigger != nil {
refreshTrigger!()
}
}
if self.headerRefreshing {
if self.preOffset > self.threshold,
self.offset <= self.threshold {
self.headerFrozen = true
}
} else {
self.headerFrozen = false
}
self.preOffset = self.offset
print("滑动位置偏移：\(self.offset)")
//加载更多触发条件
//print("内容高度\(listContentH)","列表物理高度：\(listSizeH)", "当前偏移量\(-(self.preOffset - listSizeH))")
if self.footerRefreshing == false,
self.footerFrozen == false,
self.preOffset < 0.0,
listContentH > 0.0 ,
(listContentH > listSizeH ? ((listContentH + threshold) <= abs(self.preOffset - listSizeH)) : abs(self.preOffset) > self.threshold) {
//if self.footerRefreshing == false && ((listContentH + threshold) <= -(self.preOffset - listSizeH)) && listContentH > 0.0 {
self.headerRefreshing = false
self.headerFrozen = false
self.footerRefreshing = true
if footerHidden == false {//底部控件未隐藏，允许上拉回调
if moreTrigger != nil {
moreTrigger!()
}
}
}
if self.footerRefreshing {
if listContentH > listSizeH ? ((listContentH + threshold) <= -(self.preOffset - listSizeH)) : (abs(self.preOffset) > threshold){
//if ((listContentH + threshold) <= -(self.preOffset - listSizeH)) {
self.footerFrozen = true
}
} else {
self.footerFrozen = false
}
}
}
}
目前定义了两种样式，菊花和自定义的loading图效果，可以根据需求修改
struct HeaderConfig {
var indicatorStyle:LKRefreshUIStyle = .indicator
var titleColor:Color = .gray
var titleFont:Font = Font.system(size: 16.0,weight: .regular)
var indicatorColor:Color = .gray
var refreshingTitle:String = "正在刷新数据"
var willRefreshTitle:String = "下拉刷新数据"
var dateFormatter: String
/*
let dateFormatter: DateFormatter = {
let df = DateFormatter()
df.dateFormat = "MM月dd日 HH时mm分ss秒"
return df
}()
*/
init(indicatorStyle: LKRefreshUIStyle = .indicator,
titleColor: Color = .gray,
titleFont: Font = Font.system(size: 16.0,weight: .regular),
indicatorColor: Color = .gray,
refreshingTitle: String = "正在刷新数据",
willRefreshTitle: String = "下拉刷新数据",
dateFormatter: String = "上次更新 MM-dd HH:mm") {
self.indicatorStyle = indicatorStyle
self.titleColor = titleColor
self.titleFont = titleFont
self.indicatorColor = indicatorColor
self.refreshingTitle = refreshingTitle
self.willRefreshTitle = willRefreshTitle
self.dateFormatter = dateFormatter
}
}
struct FooterConfig {
var indicatorStyle:LKRefreshUIStyle = .indicator
var titleColor:Color
var titleFont:Font
var indicatorColor:Color
var refreshingTitle:String
var willRefreshTitle:String
init(indicatorStyle:LKRefreshUIStyle = .indicator,
titleColor: Color = .gray,
titleFont: Font = Font.system(size: 16.0,weight: .regular),
indicatorColor: Color = .gray,
refreshingTitle: String = "正在加载更多数据",
willRefreshTitle: String = "上拉加载更多") {
self.indicatorStyle = indicatorStyle
self.titleColor = titleColor
self.titleFont = titleFont
self.indicatorColor = indicatorColor
self.refreshingTitle = refreshingTitle
self.willRefreshTitle = willRefreshTitle
}
}
var threshold: CGFloat = 120 //触发的临界高度
/// 下拉刷新
@Binding var headerRefreshing: Bool
/// 加载更多
@Binding var footerRefreshing: Bool
///是否隐藏头部刷新控件 默认false 不隐藏
var headerHidden: Bool
///是否隐藏尾部刷新控件 默认false 不隐藏
var footerHidden: Bool
///配置 头部刷新控件样式配置
var headerConfig:LKRefresh.HeaderConfig
///配置 尾部刷新控件样式配置
var footerConfig:LKRefresh.FooterConfig
// 下拉刷新出发回调
var refreshTrigger: (() -> Void)?
// 上拉加载更多回调
var moreTrigger: (() -> Void)?
let content: Content
init(_ threshold: CGFloat = 120,
headerRefreshing: Binding<Bool>,
footerRefreshing: Binding<Bool>,
headerHidden: Bool = false,
footerHidden: Bool = false,
headerConfig:LKRefresh.HeaderConfig = LKRefresh.HeaderConfig(),
footerConfig:LKRefresh.FooterConfig = LKRefresh.FooterConfig(),
refreshTrigger: @escaping () -> Void,
moreTrigger: @escaping () -> Void,
@ViewBuilder content: () -> Content) {
self.threshold = threshold
self._headerRefreshing = headerRefreshing
self._footerRefreshing = footerRefreshing
self.headerHidden = headerHidden
self.footerHidden = footerHidden
self.headerConfig = headerConfig
self.footerConfig = footerConfig
self.refreshTrigger = refreshTrigger
self.moreTrigger = moreTrigger
self.content = content()
}
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