我不知道單擊后如何更改影像圖示的顏色，例如，如果視窗處于活動狀態，則圖示的顏色為藍色，否則為灰色。
這是我要問的一個例子
如果您知道解決方案，請幫助我
這是完整代碼 此代碼完全正常，您可以查看
import SwiftUI
struct AllLinesView: View {
@State var currentSelection: Int = 0
var body: some View {
PagerTabView(tint: .white, selection: $currentSelection) {
Image(systemName: "bolt.fill")
.pageLabel()
Image(systemName: "flame")
.pageLabel()
Image(systemName: "person.fill")
.pageLabel()
} content: {
Color.red
.pageView(ignoresSafeArea: true, edges: .bottom)
Color.green
.pageView(ignoresSafeArea: true, edges: .bottom)
Color.yellow
.pageView(ignoresSafeArea: true, edges: .bottom)
}
.ignoresSafeArea(.container, edges: .bottom)
}
}
選項卡視圖
struct PagerTabView<Content: View, Label: View>: View {
var content: Content
var label: Label
var tint: Color
@Binding var selection: Int
init(tint:Color,selection: Binding<Int>,@ViewBuilder labels: @escaping ()->Label,@ViewBuilder content: @escaping ()->Content) {
self.content = content()
self.label = labels()
self.tint = tint
self._selection = selection
}
@State var offset: CGFloat = 0
@State var maxTabs: CGFloat = 0
@State var tabOffset: CGFloat = 0
var body: some View {
VStack(alignment: .leading,spacing: 0) {
HStack(spacing: 0) {
label
}
.overlay(
HStack(spacing: 0) {
ForEach(0..<Int(maxTabs), id: \.self) { index in
Rectangle()
.fill(Color.black.opacity(0.01))
.onTapGesture {
let newOffset = CGFloat(index) * getScreenBounds().width
self.offset = newOffset
}
}
}
)
.foregroundColor(tint)
Capsule()
.fill(tint)
.frame(width: maxTabs == 0 ? 0 : (getScreenBounds().width / maxTabs), height: 2)
.padding(.top, 10)
.frame(maxWidth: .infinity, alignment: .leading)
.offset(x: tabOffset)
OffsetPageTabView(selection: $selection,offset: $offset) {
HStack(spacing: 0) {
content
}
.overlay(
GeometryReader { proxy in
Color.clear
.preference(key: TabPreferenceKey.self, value: proxy.frame(in: .global))
}
)
.onPreferenceChange(TabPreferenceKey.self) { proxy in
let minX = -proxy.minX
let maxWidth = proxy.width
let screenWidth = getScreenBounds().width
let maxTabs = (maxWidth / screenWidth).rounded()
let progress = minX / screenWidth
let tabOffset = progress * (screenWidth / maxTabs)
self.tabOffset = tabOffset
self.maxTabs = maxTabs
}
}
}
}
}
TabPreferenceKey
struct TabPreferenceKey: PreferenceKey {
static var defaultValue: CGRect = .init()
static func reduce(value: inout CGRect, nextValue: () -> CGRect) {
value = nextValue()
}
}
pageLabel - pageView
extension View {
//IMAGE
func pageLabel()->some View {
self
.frame(maxWidth: .infinity, alignment: .center)
}
//PAGE
func pageView(ignoresSafeArea: Bool = false, edges: Edge.Set = [])->some View {
self
.frame(width: getScreenBounds().width, alignment: .center)
.ignoresSafeArea(ignoresSafeArea ? .container : .init(), edges: edges)
}
func getScreenBounds()->CGRect {
return UIScreen.main.bounds
}
}
偏移頁
struct OffsetPageTabView<Content: View>: UIViewRepresentable {
var content: Content
@Binding var offset: CGFloat
@Binding var selection: Int
func makeCoordinator() -> Coordinator {
return OffsetPageTabView.Coordinator(parent: self)
}
init(selection: Binding<Int>,offset: Binding<CGFloat>, @ViewBuilder content: @escaping ()->Content) {
self.content = content()
self._offset = offset
self._selection = selection
}
func makeUIView(context: Context) -> UIScrollView {
let scrollview = UIScrollView()
let hostview = UIHostingController(rootView: content)
hostview.view.translatesAutoresizingMaskIntoConstraints = false
let constraints = [
hostview.view.topAnchor.constraint(equalTo: scrollview.topAnchor),
hostview.view.leadingAnchor.constraint(equalTo: scrollview.leadingAnchor),
hostview.view.trailingAnchor.constraint(equalTo: scrollview.trailingAnchor),
hostview.view.bottomAnchor.constraint(equalTo: scrollview.bottomAnchor),
hostview.view.heightAnchor.constraint(equalTo: scrollview.heightAnchor)
]
scrollview.addSubview(hostview.view)
scrollview.addConstraints(constraints)
scrollview.isPagingEnabled = true
scrollview.showsVerticalScrollIndicator = false
scrollview.showsHorizontalScrollIndicator = false
scrollview.delegate = context.coordinator
return scrollview
}
func updateUIView(_ uiView: UIScrollView, context: Context) {
let currentOffset = uiView.contentOffset.x
if currentOffset != offset {
print("updating")
uiView.setContentOffset(CGPoint(x: offset, y: 0), animated: true)
}
}
class Coordinator: NSObject, UIScrollViewDelegate {
var parent: OffsetPageTabView
init(parent: OffsetPageTabView) {
self.parent = parent
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let offset = scrollView.contentOffset.x
let maxSize = scrollView.contentSize.width
let currentSelection = (offset / maxSize).rounded()
parent.selection = Int(currentSelection)
parent.offset = offset
}
}
}
uj5u.com熱心網友回復：
此代碼不是以易于更改的方式構建的。主要問題是它使用ViewBuilders 作為標簽和頁面，但是我們（不是 Apple 的）SwiftUI 代碼無法洞察有多少元素被傳遞到ViewBuilder這樣的物件中。因此，我不得不添加一個有點丑陋的技巧，即手動傳遞子視圖的數量。我還必須foregroundColor為每個標簽顯式添加修飾符，這是現有代碼作業方式存在缺陷的另一個結果。
原始代碼的currentSelection邏輯被完全破壞（即根本不起作用），但一旦顯式傳遞子元素的數量就很容易修復。
查看更新的代碼，包括對更改位置的行內注釋。
struct AllLinesView: View {
@State var currentSelection: Int = 0
var body: some View {
PagerTabView(tint: .white, selection: $currentSelection, children: 3) { //<-- Here
Image(systemName: "bolt.fill")
.pageLabel()
.foregroundColor(currentSelection == 0 ? .blue : .white) //<-- Here
Image(systemName: "flame")
.pageLabel()
.foregroundColor(currentSelection == 1 ? .blue : .white) //<-- Here
Image(systemName: "person.fill")
.pageLabel()
.foregroundColor(currentSelection == 2 ? .blue : .white) //<-- Here
} content: {
Color.red
.pageView(ignoresSafeArea: true, edges: .bottom)
Color.green
.pageView(ignoresSafeArea: true, edges: .bottom)
Color.yellow
.pageView(ignoresSafeArea: true, edges: .bottom)
}
.ignoresSafeArea(.container, edges: .bottom)
.onChange(of: currentSelection) { newValue in
print(newValue)
}
}
}
struct PagerTabView<Content: View, Label: View>: View {
var content: Content
var label: Label
var tint: Color
var children: Int //<-- Here
@Binding var selection: Int
init(tint:Color,selection: Binding<Int>,children: Int, @ViewBuilder labels: @escaping ()->Label,@ViewBuilder content: @escaping ()->Content) {
self.children = children
self.content = content()
self.label = labels()
self.tint = tint
self._selection = selection
}
@State var offset: CGFloat = 0
@State var maxTabs: CGFloat = 0
@State var tabOffset: CGFloat = 0
var body: some View {
VStack(alignment: .leading,spacing: 0) {
HStack(spacing: 0) {
label
}
.overlay(
HStack(spacing: 0) {
ForEach(0..<Int(maxTabs), id: \.self) { index in
Rectangle()
.fill(Color.black.opacity(0.01))
.onTapGesture {
let newOffset = CGFloat(index) * getScreenBounds().width
self.offset = newOffset
}
}
}
)
.foregroundColor(tint)
Capsule()
.fill(tint)
.frame(width: maxTabs == 0 ? 0 : (getScreenBounds().width / maxTabs), height: 2)
.padding(.top, 10)
.frame(maxWidth: .infinity, alignment: .leading)
.offset(x: tabOffset)
OffsetPageTabView(selection: $selection,offset: $offset, children: children) { //<-- Here
HStack(spacing: 0) {
content
}
.overlay(
GeometryReader { proxy in
Color.clear
.preference(key: TabPreferenceKey.self, value: proxy.frame(in: .global))
}
)
.onPreferenceChange(TabPreferenceKey.self) { proxy in
let minX = -proxy.minX
let maxWidth = proxy.width
let screenWidth = getScreenBounds().width
let maxTabs = (maxWidth / screenWidth).rounded()
let progress = minX / screenWidth
let tabOffset = progress * (screenWidth / maxTabs)
self.tabOffset = tabOffset
self.maxTabs = maxTabs
}
}
}
}
}
struct TabPreferenceKey: PreferenceKey {
static var defaultValue: CGRect = .init()
static func reduce(value: inout CGRect, nextValue: () -> CGRect) {
value = nextValue()
}
}
extension View {
//IMAGE
func pageLabel()->some View {
self
.frame(maxWidth: .infinity, alignment: .center)
}
//PAGE
func pageView(ignoresSafeArea: Bool = false, edges: Edge.Set = [])->some View {
self
.frame(width: getScreenBounds().width, alignment: .center)
.ignoresSafeArea(ignoresSafeArea ? .container : .init(), edges: edges)
}
func getScreenBounds()->CGRect {
return UIScreen.main.bounds
}
}
struct OffsetPageTabView<Content: View>: UIViewRepresentable {
var content: Content
@Binding var offset: CGFloat
@Binding var selection: Int
var children: Int //<-- Here
func makeCoordinator() -> Coordinator {
return OffsetPageTabView.Coordinator(parent: self)
}
init(selection: Binding<Int>,offset: Binding<CGFloat>, children: Int, @ViewBuilder content: @escaping ()->Content) {
self.content = content()
self._offset = offset
self._selection = selection
self.children = children
}
func makeUIView(context: Context) -> UIScrollView {
let scrollview = UIScrollView()
let hostview = UIHostingController(rootView: content)
hostview.view.translatesAutoresizingMaskIntoConstraints = false
let constraints = [
hostview.view.topAnchor.constraint(equalTo: scrollview.topAnchor),
hostview.view.leadingAnchor.constraint(equalTo: scrollview.leadingAnchor),
hostview.view.trailingAnchor.constraint(equalTo: scrollview.trailingAnchor),
hostview.view.bottomAnchor.constraint(equalTo: scrollview.bottomAnchor),
hostview.view.heightAnchor.constraint(equalTo: scrollview.heightAnchor)
]
scrollview.addSubview(hostview.view)
scrollview.addConstraints(constraints)
scrollview.isPagingEnabled = true
scrollview.showsVerticalScrollIndicator = false
scrollview.showsHorizontalScrollIndicator = false
scrollview.delegate = context.coordinator
return scrollview
}
func updateUIView(_ uiView: UIScrollView, context: Context) {
let currentOffset = uiView.contentOffset.x
if currentOffset != offset {
//print("updating")
uiView.setContentOffset(CGPoint(x: offset, y: 0), animated: true)
}
}
class Coordinator: NSObject, UIScrollViewDelegate {
var parent: OffsetPageTabView
init(parent: OffsetPageTabView) {
self.parent = parent
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let offset = scrollView.contentOffset.x
let maxSize = scrollView.contentSize.width
let currentSelection = (offset / maxSize) * CGFloat(parent.children) //<-- Here
print("max: ", maxSize, offset)
print("Set selection to: ", Int(currentSelection), currentSelection)
parent.selection = Int(currentSelection)
parent.offset = offset
}
}
}
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