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Update CollectionView to support anchoring an item
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@mohamede1945
mohamede1945 committed Jan 15, 2024
1 parent 972e014 commit d78a404
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Showing 8 changed files with 1,099 additions and 134 deletions.
6 changes: 3 additions & 3 deletions .github/workflows/ci.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -14,10 +14,10 @@ jobs:
- uses: actions/checkout@v2

- name: Setting up Xcode
run: sudo xcode-select -s "/Applications/Xcode_14.3.app"
run: sudo xcode-select -s "/Applications/Xcode_15.1.app"

- name: Run tests
run: set -o pipefail && xcrun xcodebuild build test -scheme QuranEngine-Package -sdk "iphonesimulator" -destination "name=iPhone 14 Pro,OS=16.4" | xcpretty
run: set -o pipefail && xcrun xcodebuild build test -scheme QuranEngine-Package -sdk "iphonesimulator" -destination "name=iPhone 14 Pro,OS=17.2" | xcpretty

- uses: codecov/codecov-action@v3
with:
Expand All @@ -30,7 +30,7 @@ jobs:
- uses: actions/checkout@v2

- name: Setting up Xcode
run: sudo xcode-select -s "/Applications/Xcode_14.3.app"
run: sudo xcode-select -s "/Applications/Xcode_15.1.app"

- name: Build
run: set -o pipefail && xcrun xcodebuild build -workspace Example/QuranEngineApp.xcworkspace -scheme QuranEngineApp -sdk "iphonesimulator" -destination 'generic/platform=iOS' CODE_SIGN_IDENTITY="" CODE_SIGNING_REQUIRED=NO | xcpretty
1 change: 1 addition & 0 deletions Package.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -160,6 +160,7 @@ private func uiTargets() -> [[Target]] {
target(type, name: "ViewConstrainer", hasTests: false),
target(type, name: "UIx", hasTests: false, dependencies: [
"ViewConstrainer",
"VLogging",
]),
target(type, name: "NoorFont", hasTests: false, resources: [
.process("Resources"),
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200 changes: 76 additions & 124 deletions UI/UIx/SwiftUI/CollectionView/CollectionView.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,10 @@

import SwiftUI

public enum ScrollAnchor {
case center
}

public struct CollectionView<
SectionId: Hashable,
Item: Identifiable & Hashable,
Expand All @@ -17,7 +21,7 @@ public struct CollectionView<
public init(
layout: UICollectionViewLayout,
sections: [ListSection<SectionId, Item>],
content: @escaping (SectionId, Item) -> ItemContent
@ViewBuilder content: @escaping (SectionId, Item) -> ItemContent
) {
self.layout = layout
self.sections = sections
Expand All @@ -31,14 +35,33 @@ public struct CollectionView<
layout: layout,
sections: sections,
configure: configure,
content: content
content: content,
isPagingEnabled: isPagingEnabled,
scrollAnchorId: scrollAnchorId,
scrollAnchor: scrollAnchor
)
}

public func configureCollectionView(configure: @escaping (UICollectionView) -> Void) -> Self {
var collectionView = self
collectionView.configure = configure
return collectionView
mutateSelf {
$0.configure = configure
}
}

public func anchorScrollTo(
id scrollAnchorId: Binding<Item.ID>,
anchor: ScrollAnchor = .center
) -> Self {
mutateSelf {
$0.scrollAnchorId = scrollAnchorId
$0.scrollAnchor = anchor
}
}

public func pagingEnabled(_ isPagingEnabled: Bool) -> Self {
mutateSelf {
$0.isPagingEnabled = isPagingEnabled
}
}

// MARK: Private
Expand All @@ -47,14 +70,19 @@ public struct CollectionView<
private let sections: [ListSection<SectionId, Item>]
private let content: (SectionId, Item) -> ItemContent
private var configure: ((UICollectionView) -> Void)?

private var isPagingEnabled: Bool = false

private var scrollAnchorId: Binding<Item.ID>?
private var scrollAnchor: ScrollAnchor = .center
}

private struct CollectionViewBody<
SectionId: Hashable,
Item: Identifiable & Hashable,
ItemContent: View
>: UIViewControllerRepresentable {
typealias UIViewControllerType = CollectionViewController<ItemContent>
typealias UIViewControllerType = CollectionViewController<SectionId, Item, ItemContent>

// MARK: Internal

Expand All @@ -63,14 +91,16 @@ private struct CollectionViewBody<
let configure: ((UICollectionView) -> Void)?
let content: (SectionId, Item) -> ItemContent

let isPagingEnabled: Bool

let scrollAnchorId: Binding<Item.ID>?
let scrollAnchor: ScrollAnchor

func makeUIViewController(context: Context) -> UIViewControllerType {
let viewController = UIViewControllerType(collectionViewLayout: layout)
viewController.collectionView.backgroundColor = .clear
let viewController = UIViewControllerType(collectionViewLayout: layout, content: content)
configure?(viewController.collectionView)

context.coordinator.viewController = viewController
context.coordinator.setUpDataSource(content: content)

updateUIViewController(viewController, context: context)

return viewController
Expand All @@ -91,7 +121,15 @@ private struct CollectionViewBody<
viewController.collectionView.collectionViewLayout = layout
}

context.coordinator.updateData(sections: sections)
viewController.dataSource?.sections = sections

viewController.scroller.isPagingEnabled = isPagingEnabled
viewController.scroller.onScrollAnchorIdUpdated = {
scrollAnchorId?.wrappedValue = $0
}
if let scrollAnchorId {
viewController.scroller.anchorScrollTo(id: scrollAnchorId.wrappedValue, anchor: scrollAnchor)
}
}

func makeCoordinator() -> Coordinator {
Expand All @@ -101,112 +139,11 @@ private struct CollectionViewBody<

extension CollectionViewBody {
class Coordinator {
// MARK: Lifecycle

init(_ parent: CollectionViewBody) {
self.parent = parent
}

// MARK: Internal

let parent: CollectionViewBody
var dataSource: UICollectionViewDiffableDataSource<SectionId, Item.ID>?
weak var viewController: UIViewControllerType?

func updateData(sections: [ListSection<SectionId, Item>]) {
let oldSections = self.sections
self.sections = sections

updateData(oldSections: oldSections, newSections: sections)
}

func setUpDataSource(content: @escaping (SectionId, Item) -> ItemContent) {
guard let viewController else {
fatalError("setUpDataSource called before setting the viewController.")
}

let cellType = UIViewControllerType.CellType.self
viewController.collectionView.register(cellType, forCellWithReuseIdentifier: cellType.reuseId)

dataSource = UICollectionViewDiffableDataSource(collectionView: viewController.collectionView) {
[weak self] _, indexPath, itemId in
guard let self, let viewController = self.viewController else {
return UICollectionViewCell()
}

// Get the item.
let section = sections[indexPath.section]
let item = sections[indexPath.section].items[indexPath.item]
assert(item.id == itemId, "Sections data doesn't match data source snapshot.")

// Get & configure the cell.
let cell = viewController.collectionView.dequeueReusableCell(UIViewControllerType.CellType.self, for: indexPath)
cell.configure(content: content(section.id, item), dataId: itemId)

return cell
}
}

// MARK: Private

private var sections: [ListSection<SectionId, Item>] = []

private func updateData(
oldSections: [ListSection<SectionId, Item>],
newSections: [ListSection<SectionId, Item>]
) {
guard let dataSource else {
return
}

var snapshot = dataSource.snapshot()
var hasDataSourceChanged = false
defer {
if hasDataSourceChanged {
dataSource.apply(snapshot, animatingDifferences: false)
}
}

// Early return for initial update.
guard !oldSections.isEmpty else {
hasDataSourceChanged = true

snapshot.deleteAllItems()
for newSection in newSections {
snapshot.appendSections([newSection.sectionId])
snapshot.appendItems(newSection.items.map(\.id))
}
return
}

// Build new snapshot, if any item/section id changed.
let oldSectionIds = oldSections.map(\.sectionId)
let newSectionIds = newSections.map(\.sectionId)
let oldItemIds = oldSections.map { $0.items.map(\.id) }
let newItemIds = newSections.map { $0.items.map(\.id) }

if oldSectionIds != newSectionIds || oldItemIds != newItemIds {
hasDataSourceChanged = true
snapshot = .init()
for newSection in newSections {
snapshot.appendSections([newSection.sectionId])
snapshot.appendItems(newSection.items.map(\.id))
}
}

// Reload updated items.
let allOldItems = oldSections.flatMap(\.items)
let oldItemsDictionary = Dictionary(grouping: allOldItems, by: \.id).mapValues(\.first)

let allNewItems = newSections.flatMap(\.items)
let newItemsDictionary = Dictionary(grouping: allNewItems, by: \.id).mapValues(\.first)

for (itemId, newItem) in newItemsDictionary {
if newItem != oldItemsDictionary[itemId] {
hasDataSourceChanged = true
snapshot.backwardCompatibleReconfigureItems([itemId])
}
}
init(_ parent: CollectionViewBody) {
self.parent = parent
}
}
}
Expand All @@ -229,7 +166,9 @@ struct StaticCollectionView_Previews: PreviewProvider {
)
let item = NSCollectionLayoutItem(layoutSize: size)
let group = NSCollectionLayoutGroup.horizontal(layoutSize: size, subitem: item, count: 1)
let collectionViewLayout = UICollectionViewCompositionalLayout(section: .init(group: group))
let section = NSCollectionLayoutSection(group: group)
section.interGroupSpacing = 60
let collectionViewLayout = UICollectionViewCompositionalLayout(section: section)
return collectionViewLayout
}()

Expand All @@ -240,17 +179,30 @@ struct StaticCollectionView_Previews: PreviewProvider {
),
]

@State var scrollAnchorId: Int = 45 {
didSet {
print("Scrolled to item \(scrollAnchorId)")
}
}

var body: some View {
CollectionView(layout: layout, sections: sections) { _, item in
VStack {
Text("\(item.text.uppercased())")
.fontWeight(.bold)
.padding()
Divider()
ZStack {
CollectionView(layout: layout, sections: sections) { _, item in
VStack {
Text(item.text)
.padding()
Divider()
}
.border(.purple)
}
}
.configureCollectionView { collectionView in
collectionView.contentInsetAdjustmentBehavior = .never
.configureCollectionView { collectionView in
collectionView.contentInsetAdjustmentBehavior = .never
}
.anchorScrollTo(id: $scrollAnchorId)

Circle()
.foregroundColor(.purple)
.frame(width: 10)
}
}
}
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