Uiview PageViewController-白色背景

我正在尝试对由PageViewController表示的卡应用.background修改器

红色背景不适用于我的卡，因为该卡似乎有默认的白色背景

这里有什么问题？

---

非常感谢。

默认情况下，您的UIHostingController会为每一张确切的卡设置背景。您可以将背景颜色设置为。手动清除可使SwiftUI背景生效：

struct PageView<Page:View>: View {

    var viewControllers: [UIHostingController<Page>]

    init(_ views: [Page]) {
        self.viewControllers = views.map { UIHostingController(rootView: $0)}
        for viewController in viewControllers{
            viewController.view.backgroundColor = .clear
        }

    }
...
}

struct页面视图：视图{
var viewControllers:[UIHostingController]
初始化（uu视图：[页面]）{
self.viewControllers=views.map{UIHostingController（rootView:$0）}
对于viewController中的viewController{
viewController.view.backgroundColor=.clear
}
}
...
}

检查我的完整

SwiftUI

实现

UIPageViewController

。它不使用

UIKit

，因此更易于控制

import SwiftUI
extension OnboardingCard{
    static var test: [OnboardingCard]{
        [
        OnboardingCard(image: "onboarding", title: "Card 1", description: "Card 1 description."),
        OnboardingCard(image: "onboarding", title: "Card 2", description: "Card 2 description."),
        OnboardingCard(image: "onboarding", title: "Card 3", description: "Card 4 description.")
        ]
    }
}

struct ContentView: View {
    var directionForward = true
    @State var currentCard: OnboardingCard
    var cards: [OnboardingCard]
    @State var xOffset: CGFloat = 0
    init(cards newCards: [OnboardingCard]){
        self.cards = newCards
        guard let startCard = newCards.first else {fatalError("no cards")}
        self._currentCard = State(initialValue: startCard)
    }
    var body: some View {
        GeometryReader{geometry in
            HStack{
                ForEach(self.cardsSorted()){card in
                    OnboardingCardView(card: card)
                        .frame(width: geometry.size.width)
                }
            }
            .offset(x: self.xOffset, y: 0)
            .gesture(DragGesture()
            .onChanged(){value in
                self.xOffset = value.location.x - value.startLocation.x
                }
            .onEnded(){value in
                let inPercent = 100 * self.xOffset / (geometry.size.width / 2)
                let changedCount = inPercent / 100
                if changedCount < -1{//drag left to go to next one
                    guard let currentCardInd = self.cards.firstIndex(where: {$0.id == self.currentCard.id}) else{fatalError("cant find current card")}
                    let nextInd = self.cards.index(currentCardInd, offsetBy: Int(-changedCount))
                    if self.cards.indices.contains(nextInd){
                        self.currentCard = self.cards[nextInd]
                        self.xOffset = geometry.size.width + self.xOffset
                    }else{
                        guard let firstCard = self.cards.first else{fatalError("cant get first card")}
                        self.currentCard = firstCard
                        self.xOffset = geometry.size.width + self.xOffset
                    }
                }else if changedCount > 1{//drag right to go to previos one
                    guard let currentCardInd = self.cards.firstIndex(where: {$0.id == self.currentCard.id}) else{fatalError("cant find current card")}
                    let previosInd = self.cards.index(currentCardInd, offsetBy: Int(-changedCount))
                    if self.cards.indices.contains(previosInd){
                        self.currentCard = self.cards[previosInd]
                        self.xOffset = -geometry.size.width + self.xOffset
                    }else{
                        guard let lastCard = self.cards.last else{fatalError("cant get last card")}
                        self.currentCard = lastCard
                        self.xOffset = -geometry.size.width + self.xOffset
                    }
                }

                withAnimation(.easeInOut(duration: 0.5)){
                    self.xOffset = 0
                }
            })
        }
    }
    func cardsSorted() -> [OnboardingCard]{
        guard let currentCardInd = self.cards.firstIndex(where: {$0.id == self.currentCard.id}) else{fatalError("cant find current card")}
        guard let firstInd = self.cards.firstIndex(where: {$0.id == cards.first?.id}) else{fatalError("cant find current card")}
        guard let lastInd = self.cards.firstIndex(where: {$0.id == cards.last?.id}) else{fatalError("cant find current card")}
        var nextInd = self.cards.index(after: currentCardInd)
        if self.cards.indices.contains(nextInd) == false{
            nextInd = firstInd
        }
        var previosInd = self.cards.index(before: currentCardInd)
        if self.cards.indices.contains(previosInd) == false{
            previosInd = lastInd
        }
        return [self.cards[previosInd], self.cards[currentCardInd],self.cards[nextInd]]
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView(cards: OnboardingCard.test)
    }
}

导入快捷界面
分机登机卡{
静态var测试：[车载卡]{
[
登机卡（图像：“登机”，标题：“卡1”，说明：“卡1说明”），
登机卡（图像：“登机”，标题：“卡2”，说明：“卡2说明”），
登机卡（图像：“登机”，标题：“卡3”，说明：“卡4说明”）
]
}
}
结构ContentView:View{
var directionForward=true
@状态变量当前卡：车载卡
var卡：[车载卡]
@状态变量xOffset:CGFloat=0
初始化（新卡：[车载卡]）{
self.cards=新卡
guard let startCard=newCards.first-else{fatalError（“无卡”）}
self.\u currentCard=状态（初始值：startCard）
}
var body：一些观点{
GeometryReader{中的几何体
HStack{
ForEach（self.cardsorted（））{card-in
车载卡视图（卡：卡）
.框架（宽度：几何尺寸宽度）
}
}
.offset（x:self.xOffset，y:0）
.手势（DragGesture（）
.onChanged（）{中的值
self.xOffset=value.location.x-value.startLocation.x
}
.onEnded（）{中的值
设输入百分比=100*self.xOffset/（geometry.size.width/2）
让changedCount=inPercent/100
如果changedCount<-1{//向左拖动以转到下一个
guard let currentCardInd=self.cards.firstIndex（其中：{$0.id==self.currentCard.id}）else{fatalError（“找不到当前卡”）}
设nextInd=self.cards.index（currentCardInd，offsetBy:Int（-changedCount））
如果self.cards.index.contains（nextInd）{
self.currentCard=self.cards[nextInd]
self.xOffset=geometry.size.width+self.xOffset
}否则{
guard let firstCard=self.cards.first-else{fatalError（“无法获得第一张卡”）}
self.currentCard=firstCard
self.xOffset=geometry.size.width+self.xOffset
}
}否则，如果changedCount>1{//则向右拖动以转到previos one
guard let currentCardInd=self.cards.firstIndex（其中：{$0.id==self.currentCard.id}）else{fatalError（“找不到当前卡”）}
让previosInd=self.cards.index（currentCardInd，offsetBy:Int（-changedCount））
如果self.cards.index.contains（previosInd）{
self.currentCard=self.cards[previosInd]
self.xOffset=-geometry.size.width+self.xOffset
}否则{
guard let lastCard=self.cards.last else{fatalError（“无法获取最后一张卡”）}
self.currentCard=lastCard
self.xOffset=-geometry.size.width+self.xOffset
}
}
带动画（.easeInOut（持续时间：0.5））{
self.xOffset=0
}
})
}
}
func Cardsorted（）->[车载卡]{
guard let currentCardInd=self.cards.firstIndex（其中：{$0.id==self.currentCard.id}）else{fatalError（“找不到当前卡”）}
guard let firstInd=self.cards.firstIndex（其中：{$0.id==cards.first？.id}）else{fatalError（“找不到当前卡”）}
guard let lastInd=self.cards.firstIndex（其中：{$0.id==cards.last？.id}）else{fatalError（“找不到当前卡”）}
var nextInd=self.cards.index（在：currentCardInd之后）
如果self.cards.index.contains（nextInd）=false{
nextInd=firstInd
}
var previosInd=self.cards.index（在：currentCardInd之前）
如果self.cards.index.contains（previosInd）=false{
previosInd=lastInd
}
返回[self.cards[previosInd]，self.cards[currentCardInd]，self.cards[nextInd]]
}
}
结构内容视图\u预览：PreviewProvider{
静态var预览：一些视图{
ContentView（卡片：OnboardingCard.test）
}
}

---

它的代码更少，逻辑也更透明。如果需要，您可以修改检查以调整开关灵敏度（通过编辑compare

if changedCount>1

）。您可以使用手势端点预测来计算和调整动画速度，甚至可以一次切换多张卡。这完全取决于你。或者您可以按原样使用。

谢谢您的回答@Aspid。我不在PageViewController中设置背景。我添加了代码以便您更好地理解。我仍然对这个问题耿耿于怀，我想了解发生了什么。更深入地了解

UIPageViewController

？感谢您的帮助，这是我的完整代码项目示例：问题在UIPageViewController中。默认情况下，它不是透明的。检查这个问题是否有帮助：非常感谢！没有UIKit肯定会更好。我

struct PageView<Page:View>: View {

    var viewControllers: [UIHostingController<Page>]

    init(_ views: [Page]) {
        self.viewControllers = views.map { UIHostingController(rootView: $0)}
        for viewController in viewControllers{
            viewController.view.backgroundColor = .clear
        }

    }
...
}

import SwiftUI
extension OnboardingCard{
    static var test: [OnboardingCard]{
        [
        OnboardingCard(image: "onboarding", title: "Card 1", description: "Card 1 description."),
        OnboardingCard(image: "onboarding", title: "Card 2", description: "Card 2 description."),
        OnboardingCard(image: "onboarding", title: "Card 3", description: "Card 4 description.")
        ]
    }
}

struct ContentView: View {
    var directionForward = true
    @State var currentCard: OnboardingCard
    var cards: [OnboardingCard]
    @State var xOffset: CGFloat = 0
    init(cards newCards: [OnboardingCard]){
        self.cards = newCards
        guard let startCard = newCards.first else {fatalError("no cards")}
        self._currentCard = State(initialValue: startCard)
    }
    var body: some View {
        GeometryReader{geometry in
            HStack{
                ForEach(self.cardsSorted()){card in
                    OnboardingCardView(card: card)
                        .frame(width: geometry.size.width)
                }
            }
            .offset(x: self.xOffset, y: 0)
            .gesture(DragGesture()
            .onChanged(){value in
                self.xOffset = value.location.x - value.startLocation.x
                }
            .onEnded(){value in
                let inPercent = 100 * self.xOffset / (geometry.size.width / 2)
                let changedCount = inPercent / 100
                if changedCount < -1{//drag left to go to next one
                    guard let currentCardInd = self.cards.firstIndex(where: {$0.id == self.currentCard.id}) else{fatalError("cant find current card")}
                    let nextInd = self.cards.index(currentCardInd, offsetBy: Int(-changedCount))
                    if self.cards.indices.contains(nextInd){
                        self.currentCard = self.cards[nextInd]
                        self.xOffset = geometry.size.width + self.xOffset
                    }else{
                        guard let firstCard = self.cards.first else{fatalError("cant get first card")}
                        self.currentCard = firstCard
                        self.xOffset = geometry.size.width + self.xOffset
                    }
                }else if changedCount > 1{//drag right to go to previos one
                    guard let currentCardInd = self.cards.firstIndex(where: {$0.id == self.currentCard.id}) else{fatalError("cant find current card")}
                    let previosInd = self.cards.index(currentCardInd, offsetBy: Int(-changedCount))
                    if self.cards.indices.contains(previosInd){
                        self.currentCard = self.cards[previosInd]
                        self.xOffset = -geometry.size.width + self.xOffset
                    }else{
                        guard let lastCard = self.cards.last else{fatalError("cant get last card")}
                        self.currentCard = lastCard
                        self.xOffset = -geometry.size.width + self.xOffset
                    }
                }

                withAnimation(.easeInOut(duration: 0.5)){
                    self.xOffset = 0
                }
            })
        }
    }
    func cardsSorted() -> [OnboardingCard]{
        guard let currentCardInd = self.cards.firstIndex(where: {$0.id == self.currentCard.id}) else{fatalError("cant find current card")}
        guard let firstInd = self.cards.firstIndex(where: {$0.id == cards.first?.id}) else{fatalError("cant find current card")}
        guard let lastInd = self.cards.firstIndex(where: {$0.id == cards.last?.id}) else{fatalError("cant find current card")}
        var nextInd = self.cards.index(after: currentCardInd)
        if self.cards.indices.contains(nextInd) == false{
            nextInd = firstInd
        }
        var previosInd = self.cards.index(before: currentCardInd)
        if self.cards.indices.contains(previosInd) == false{
            previosInd = lastInd
        }
        return [self.cards[previosInd], self.cards[currentCardInd],self.cards[nextInd]]
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView(cards: OnboardingCard.test)
    }
}