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implementation of infinite scroll carousel using SwiftUI
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| import SwiftUI | |
| struct Carousel<Data: RandomAccessCollection, Content: View>: View where Data.Index: Hashable { | |
| let data: Data | |
| let content: (Data.Element) -> Content | |
| let shouldFitWidth: Bool | |
| let shouldFitHeight: Bool | |
| @Binding var currentIndex: Int | |
| @State private var selection = 0 | |
| @State private var reachedLowerBound = false { | |
| didSet { | |
| guard reachedLowerBound else { return } | |
| selection = data.count - 1 | |
| } | |
| } | |
| @State private var reachedUpperBound = false { | |
| didSet { | |
| guard reachedUpperBound else { return } | |
| selection = 0 | |
| } | |
| } | |
| @State private var contentSize: CGSize? | |
| init( | |
| _ data: Data, | |
| currentIndex: Binding<Int>? = nil, | |
| shouldFitWidth: Bool = false, | |
| shouldFitHeight: Bool = true, | |
| @ViewBuilder content: @escaping (Data.Element) -> Content | |
| ) { | |
| self.data = data | |
| self.shouldFitWidth = shouldFitWidth | |
| self.shouldFitHeight = shouldFitHeight | |
| self.content = content | |
| self._currentIndex = currentIndex ?? Binding<Int> { 0 } set: { _ in } | |
| selection = self.currentIndex | |
| } | |
| var body: some View { | |
| if data.isEmpty { | |
| EmptyView() | |
| } else { | |
| TabView(selection: $selection) { | |
| GeometryReader { geometry in | |
| contentView(data.last!) | |
| .frame(width: geometry.size.width, height: geometry.size.height) | |
| .onAppear { | |
| reachedLowerBound = 0 <= geometry.frame(in: .global).minX | |
| } | |
| .onChange(of: geometry.frame(in: .global)) { frame in | |
| reachedLowerBound = 0 <= frame.minX | |
| } | |
| } | |
| { array in | |
| ForEach(array.indices, id: \.self) { index in | |
| contentView(array[index]) | |
| } | |
| }(Array(data)) | |
| GeometryReader { geometry in | |
| contentView(data.first!) | |
| .frame(width: geometry.size.width, height: geometry.size.height) | |
| .onAppear { | |
| reachedUpperBound = geometry.frame(in: .global).minX <= 0 | |
| } | |
| .onChange(of: geometry.frame(in: .global)) { frame in | |
| reachedUpperBound = frame.minX <= 0 | |
| } | |
| } | |
| } | |
| .tabViewStyle(.page(indexDisplayMode: .never)) | |
| .onChange(of: selection) { | |
| currentIndex = $0 | |
| } | |
| .frame( | |
| maxWidth: shouldFitWidth ? contentSize?.height ?? .infinity : .infinity, | |
| maxHeight: shouldFitHeight ? contentSize?.height ?? .infinity : .infinity | |
| ) | |
| } | |
| } | |
| @ViewBuilder | |
| func contentView(_ element: Data.Element) -> some View { | |
| if shouldFitWidth || shouldFitHeight { | |
| content(element) | |
| .background { | |
| GeometryReader { geometry in | |
| Color.clear | |
| .onAppear { | |
| let effectiveSize = geometry.frame(in: .global).size | |
| if let contentSize { | |
| self.contentSize = CGSize( | |
| width: max(contentSize.width, effectiveSize.width), | |
| height: max(contentSize.height, effectiveSize.height) | |
| ) | |
| } else { | |
| self.contentSize = effectiveSize | |
| } | |
| } | |
| } | |
| } | |
| } else { | |
| content(element) | |
| } | |
| } | |
| } | |
| #Preview { | |
| struct DummyView: View { | |
| @State var currentIndex = 0 | |
| var body: some View { | |
| Carousel(["hare", "tortoise", "dog", "cat", "lizard", "bird", "ant", "ladybug", "fish"], currentIndex: $currentIndex) { | |
| Image(systemName: $0) | |
| .resizable() | |
| .aspectRatio(contentMode: .fit) | |
| .padding(24) | |
| } | |
| .overlay(alignment: .bottom) { | |
| Text(verbatim: "\(currentIndex) page") | |
| } | |
| } | |
| } | |
| return DummyView() | |
| } | |
| #Preview { | |
| struct Dummy: View { | |
| @State var selection = 0 | |
| var body: some View { | |
| Carousel((0...3), currentIndex: $selection, shouldFitHeight: false) { | |
| Text(verbatim: "page \($0)") | |
| } | |
| .overlay(alignment: .bottom) { | |
| Text("selection: \(selection)") | |
| } | |
| } | |
| } | |
| return Dummy() | |
| } |
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