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WIP #65

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4 changes: 4 additions & 0 deletions Development/Development.xcodeproj/project.pbxproj
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@
4BEAFA4C2A3CE48800478C59 /* AsyncMultiplexImage in Frameworks */ = {isa = PBXBuildFile; productRef = 4BEAFA4B2A3CE48800478C59 /* AsyncMultiplexImage */; };
4BEAFA4E2A3CE48800478C59 /* AsyncMultiplexImage-Nuke in Frameworks */ = {isa = PBXBuildFile; productRef = 4BEAFA4D2A3CE48800478C59 /* AsyncMultiplexImage-Nuke */; };
4BEBA5682D3EC5A200BDE020 /* BookRerender.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBA5672D3EC59A00BDE020 /* BookRerender.swift */; };
B059CA352E8E36F900879BA6 /* Hopping.swift in Sources */ = {isa = PBXBuildFile; fileRef = B059CA342E8E36F900879BA6 /* Hopping.swift */; };
B0699F292E8863750098A042 /* SelectableForEach in Frameworks */ = {isa = PBXBuildFile; productRef = B0699F282E8863750098A042 /* SelectableForEach */; };
B0699F2B2E8863790098A042 /* StickyHeader in Frameworks */ = {isa = PBXBuildFile; productRef = B0699F2A2E8863790098A042 /* StickyHeader */; };
B0699F2D2E88637D0098A042 /* RefreshControl in Frameworks */ = {isa = PBXBuildFile; productRef = B0699F2C2E88637D0098A042 /* RefreshControl */; };
Expand Down Expand Up @@ -62,6 +63,7 @@
4BD04C182B2C15E100FE41D9 /* Color.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Color.swift; sourceTree = "<group>"; };
4BEAFA482A3CE3B100478C59 /* BookVariadicView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BookVariadicView.swift; sourceTree = "<group>"; };
4BEBA5672D3EC59A00BDE020 /* BookRerender.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BookRerender.swift; sourceTree = "<group>"; };
B059CA342E8E36F900879BA6 /* Hopping.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Hopping.swift; sourceTree = "<group>"; };
/* End PBXFileReference section */

/* Begin PBXFrameworksBuildPhase section */
Expand Down Expand Up @@ -105,6 +107,7 @@
4B26A6792A33239500B75FB4 /* Development */ = {
isa = PBXGroup;
children = (
B059CA342E8E36F900879BA6 /* Hopping.swift */,
4BEBA5672D3EC59A00BDE020 /* BookRerender.swift */,
4B9223612D3CE6B5007E20CB /* GlobalCounter.swift */,
4B08E0AA2CF5805200B05999 /* BookScrollView.swift */,
Expand Down Expand Up @@ -235,6 +238,7 @@
4B08E0AB2CF5805500B05999 /* BookScrollView.swift in Sources */,
4BC34FB12CDB1C0C00D22811 /* BookCollectionView.swift in Sources */,
4BD04C152B2C05C600FE41D9 /* BookPlainCollectionView.swift in Sources */,
B059CA352E8E36F900879BA6 /* Hopping.swift in Sources */,
4B910EBC2A77A2F50079D26D /* BookUIKitBasedFlow.swift in Sources */,
);
runOnlyForDeploymentPostprocessing = 0;
Expand Down
301 changes: 301 additions & 0 deletions Development/Development/Hopping.swift
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Original file line number Diff line number Diff line change
@@ -0,0 +1,301 @@
import CollectionView
import SwiftUI

@available(iOS 17.0, *)
public struct HoppingLayout<Selection: Hashable>: CollectionViewLayoutType {

private let scrollPosition: Binding<Selection?>?

public init(
selection: Binding<Selection?>
) {
self.scrollPosition = selection
}

public init() where Selection == Never {
self.scrollPosition = nil
}

public func body(content: Content) -> some View {
let view = ScrollView(.vertical, showsIndicators: false) {
// In iOS17, scrollTargetLayout only works if its content is LazyVStack.
UnaryViewReader(readingContent: content) { children in
LazyVStack(spacing: 16) {
ForEach(children, id: \.id) { child in
child
.containerRelativeFrame(.vertical)
}
}
.scrollTargetLayout()
}
}
.scrollTargetBehavior(.viewAligned)
.safeAreaPadding(.vertical, 32)

if let scrollPosition {
ScrollViewReader { proxy in
view
.animation(
.smooth,
body: {
$0.scrollPosition(id: scrollPosition)
}
)
.onAppear {
proxy.scrollTo(scrollPosition.wrappedValue)
}
}
} else {
view
}
}

}

// MARK: workaround

/// https://movingparts.io/variadic-views-in-swiftui
struct UnaryViewReader<ReadingContent: View, Content: View>: View {

let readingContent: ReadingContent
let content: (_VariadicView_Children) -> Content

init(
readingContent: ReadingContent,
@ViewBuilder content: @escaping (_VariadicView_Children) -> Content
) {
self.readingContent = readingContent
self.content = content
}

// MARK: View

var body: some View {
_VariadicView.Tree(_UnaryView(content: content)) {
readingContent
}
}

}

struct MultiViewReader<ReadingContent: View, Content: View>: View {

let readingContent: ReadingContent
let content: (_VariadicView_Children) -> Content

init(
readingContent: ReadingContent,
@ViewBuilder content: @escaping (_VariadicView_Children) -> Content
) {
self.readingContent = readingContent
self.content = content
}

// MARK: View

var body: some View {
_VariadicView.Tree(_MultiView(content: content)) {
readingContent
}
}

}

private struct _UnaryView<Content: View>: _VariadicView_UnaryViewRoot {

let content: (_VariadicView_Children) -> Content

init(@ViewBuilder content: @escaping (_VariadicView_Children) -> Content) {
self.content = content
}

@ViewBuilder
func body(children: _VariadicView.Children) -> some View {
content(children)
}
}

private struct _MultiView<Content: View>: _VariadicView_MultiViewRoot {

let content: (_VariadicView_Children) -> Content

init(@ViewBuilder content: @escaping (_VariadicView_Children) -> Content) {
self.content = content
}

@ViewBuilder
func body(children: _VariadicView.Children) -> some View {
content(children)
}
}

#Preview("Hopping 1") {

@Previewable @State var scrollPosition: Int? = 3

VStack {
HStack {
Button("One") {
scrollPosition = 1
}
Button("Two") {
scrollPosition = 2
}
Button("Three") {
scrollPosition = 3
}
}
.buttonStyle(.bordered)

CollectionView(
layout: HoppingLayout(selection: $scrollPosition)
) {
ForEach(0..<30, id: \.self) { i in
CardItem(
title: "Item \(i)",
color: .purple
)
.id(i)
}
}
}
}

#Preview("Hopping 2") {

@Previewable @State var scrollPosition: Int? = 3

VStack {
HStack {
Button("One") {
scrollPosition = 1
}
Button("Two") {
scrollPosition = 2
}
Button("Three") {
scrollPosition = 3
}
}
.buttonStyle(.bordered)

CollectionView(
layout: HoppingLayout(selection: $scrollPosition)
) {
ForEach(0..<30, id: \.self) { i in
Text("Item \(i)")
.background(.red.opacity(0.3))
.id(i)
.id(i)
}
}
}
}

private struct CardItem: View {
let title: String
let color: Color

var body: some View {
ZStack {
color
Text(title)
.font(.title)
.fontWeight(.bold)
.foregroundColor(.white)
}
.frame(maxWidth: .infinity, maxHeight: .infinity)
.padding(.horizontal, 24)
}
}


public struct Hopping<Selection: Hashable, Content: View>: View {

private let content: Content
private let scrollPosition: Binding<Selection?>?

public init(
selection: Binding<Selection?>,
@ViewBuilder content: () -> Content
) {
self.scrollPosition = selection
self.content = content()
}

public init(
@ViewBuilder content: () -> Content
) where Selection == Never {
self.scrollPosition = nil
self.content = content()
}

public var body: some View {


// let view = ScrollView(.vertical, showsIndicators: false) {
// // In iOS17, scrollTargetLayout only works if its content is LazyVStack.
// UnaryViewReader(readingContent: content) { children in
// LazyVStack(spacing: 16) {
// ForEach(children, id: \.id) { child in
// child
// .containerRelativeFrame(.vertical)
// }
// }
// .scrollTargetLayout()
// }
// }
// .scrollTargetBehavior(.viewAligned)
// .safeAreaPadding(.vertical, 32)
//
// if let scrollPosition {
// ScrollViewReader { proxy in
// view
// .animation(
// .smooth,
// body: {
// $0.scrollPosition(id: scrollPosition)
// }
// )
// .onAppear {
// proxy.scrollTo(scrollPosition.wrappedValue)
// }
// }
// } else {
// view
// }
}

}

#Preview("ScrollView") {

@Previewable @State var selection: Int? = 1

VStack {
HStack {
Button("One") {
selection = 0
}
Button("Two") {
selection = 1
}
Button("Three") {
selection = 2
}
Button("Clear") {
selection = nil
}
}
Hopping(selection: $selection) {
ForEach(0..<10, id: \.self) { i in
Text("Item \(i)")
.background(.red.opacity(0.3))
.id(i)
}
}
.onChange(of: selection, initial: true) {
print(selection)
}
}
}