如何反转 SwiftUI 动画的幻灯片过渡?

nor*_*kin 21 iphone ios swift swiftui swiftui-animation

我正在开发一系列屏幕,这些屏幕应该在按下按钮时发生变化,并且应该从右向左滑入/滑出。
一切工作正常,除了.slide过渡使其从前缘移入并移出到后缘。(从左到右)
我想反转过渡动画方向而不改变尾随/前导是什么(至少不在应用程序的整个上下文中)。

我尝试将过渡更改为.move(edge: .trailing),但随后视图从同一方向移入和移出。

import SwiftUI

struct ContentView: View {
    enum screens {
        case start, mid, final
    }
    @State var curScreen: screens = .start
    
    func changeScreen() {
        switch curScreen {
        case .start:
            curScreen = .mid
        case .mid:
            curScreen = .final
        case .final:
            return
        }
    }
    
    var body: some View {
        switch curScreen {
        case .start:
            ScreenView(callback: changeScreen, text: "Start")
                .transition(.slide)
        case .mid:
            ScreenView(callback: changeScreen, text: "Mid")
                .transition(.slide)
        case .final:
            ScreenView(callback: {}, text: "Final")
                .transition(.slide)
        }
    }
}

struct ScreenView: View {
    let callback: () -> ()
    let text: String
    var body: some View {
        Text(text)
            .padding()
            .frame(maxWidth: .infinity)
            .onTapGesture {
                withAnimation(.default) {
                    callback()
                }
            }
    }
}
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nor*_*kin 39

@Asperi已经回答了我的问题,但是当我搜索它时它没有出现在google或stackoverflow上,所以这里再次介绍算法:

如何在 SwiftUI 中反转幻灯片切换:

摘自苹果开发者文档:

static var slide: AnyTransition
// A transition that inserts by moving in from the leading edge, and removes by moving out towards the trailing edge.
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也可以写成:

AnyTransition.asymmetric(
    insertion: .move(edge: .leading),
    removal: .move(edge: .trailing)
)
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因此,要反转动画,只需翻转insertion并将removal其放入您的转换 ViewModifier 中。

由于我需要使用它几次,所以我进行了扩展,AnyTransition这样我就可以调用.transition(.backslide)

extension AnyTransition {
    static var backslide: AnyTransition {
        AnyTransition.asymmetric(
            insertion: .move(edge: .trailing),
            removal: .move(edge: .leading))}
}
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