Is it possible to change image with fade animation using same Image? (SwiftUI)

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半阙折子戏
半阙折子戏 2021-01-21 20:39

According to my logic, on tap gesture to the image it should be changed with fade animation, but actual result is that image changes without animation. Tested with Xcode 11.3.1,

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  •  隐瞒了意图╮
    2021-01-21 21:24

    Here is possible approach using one Image (for demo some small modifications made to use default images). The important changes marked with comments.

    demo

    enum ImageEnum: String {
        case img1 = "1.circle"
        case img2 = "2.circle"
        case img3 = "3.circle"
    
        func next() -> ImageEnum {
            switch self {
                case .img1: return .img2
                case .img2: return .img3
                case .img3: return .img1
            }
        }
    }
    struct QuickTest: View {
        @State private var img = ImageEnum.img1
        @State private var fadeOut = false
        var body: some View {
            Image(systemName: img.rawValue).resizable().frame(width: 300, height: 300)
                .opacity(fadeOut ? 0 : 1)
                .animation(.easeInOut(duration: 0.25))    // animatable fade in/out
                .onTapGesture {
                    self.fadeOut.toggle()                 // 1) fade out
    
                    // delayed appear
                    DispatchQueue.main.asyncAfter(deadline: .now() + 0.25) {
                        withAnimation {
                            self.img = self.img.next()    // 2) change image
                            self.fadeOut.toggle()         // 3) fade in
                        }
                    }
                }
        }
    }
    

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