SwiftUI：fullScreenCover 的半透明背景

Question

所以從技術上講，我想顯示一個加載屏幕視圖。 我正在使用fullScreenCover 。

struct ContentView: View {
    
    @State private var isLoading = false
        
    var body: some View {
        VStack {
            Text("Hello there")
            Button("Start loading") {
                isLoading.toggle()
            }
            .fullScreenCover(isPresented: $isLoading) {
                ZStack{
                    Color.black.opacity(0.5).edgesIgnoringSafeArea(.all)
                    VStack {
                        ProgressView()
                        Button("Stop loading") {
                            isLoading.toggle()
                        }
                    }
                }
            }
        }
    }
}

問題是我不能使這個加載屏幕半透明。 sheet或popover的行為方式相同。

Answer 1

這是可能方式的演示。 您可以根據需要調整視覺效果參數。

使用 Xcode 12 / iOS 14 測試。

       // ... other code
            .fullScreenCover(isPresented: $isLoading) {
                ZStack{
                    Color.black.opacity(0.5).edgesIgnoringSafeArea(.all)
                    VStack {
                        ProgressView()
                        Button("Stop loading") {
                            isLoading.toggle()
                        }
                    }
                }
                .background(BackgroundBlurView())
            }
        }
    }
}

struct BackgroundBlurView: UIViewRepresentable {
    func makeUIView(context: Context) -> UIView {
        let view = UIVisualEffectView(effect: UIBlurEffect(style: .light))
        DispatchQueue.main.async {
            view.superview?.superview?.backgroundColor = .clear
        }
        return view
    }

    func updateUIView(_ uiView: UIView, context: Context) {}
}

備份

Answer 2

Asperi 的答案很漂亮，但如果您希望背景透明且不模糊，您可以通過以下方式對其進行修改。 為了方便起見，我還將代碼移到了修飾符中。 （xcode 13.3，iOS 15.4.1）

extension View {

    func transparentFullScreenCover<Content: View>(isPresented: Binding<Bool>, content: @escaping () -> Content) -> some View {
        fullScreenCover(isPresented: isPresented) {
            ZStack {
                content()
            }
            .background(TransparentBackground())
        }
    }
}

struct TransparentBackground: UIViewRepresentable {

    func makeUIView(context: Context) -> UIView {
        let view = UIView()
        DispatchQueue.main.async {
            view.superview?.superview?.backgroundColor = .clear
        }
        return view
    }

    func updateUIView(_ uiView: UIView, context: Context) {}
}

Answer 3

建立在 f3dm76 答案之上：

我改變了它，所以后面的內容不會閃爍（這發生在我身上，因為在 fullScreenCover 后面加載了延遲圖像）。 我還想為全屏內容使用自定義過渡（或者在某些情況下根本沒有動畫），所以我也用這種方法刪除了默認動畫。

extension View {

    func transparentNonAnimatingFullScreenCover<Content: View>(isPresented: Binding<Bool>, content: @escaping () -> Content) -> some View {
        modifier(TransparentNonAnimatableFullScreenModifier(isPresented: isPresented, fullScreenContent: content))
    }
    
}

private struct TransparentNonAnimatableFullScreenModifier<FullScreenContent: View>: ViewModifier {
    
    @Binding var isPresented: Bool
    let fullScreenContent: () -> (FullScreenContent)
    
    func body(content: Content) -> some View {
        content
            .onChange(of: isPresented) { isPresented in
                UIView.setAnimationsEnabled(false)
            }
            .fullScreenCover(isPresented: $isPresented,
                             content: {
                ZStack {
                    fullScreenContent()
                }
                .background(FullScreenCoverBackgroundRemovalView())
                .onAppear {
                    if !UIView.areAnimationsEnabled {
                        UIView.setAnimationsEnabled(true)
                    }
                }
                .onDisappear {
                    if !UIView.areAnimationsEnabled {
                        UIView.setAnimationsEnabled(true)
                    }
                }
            })
    }
    
}

private struct FullScreenCoverBackgroundRemovalView: UIViewRepresentable {
    
    private class BackgroundRemovalView: UIView {
        
        override func didMoveToWindow() {
            super.didMoveToWindow()
            
            superview?.superview?.backgroundColor = .clear
        }
        
    }
    
    func makeUIView(context: Context) -> UIView {
        return BackgroundRemovalView()
    }
    
    func updateUIView(_ uiView: UIView, context: Context) {}
    
}

Answer 4

您還可以使用 Material 背景類型：

ZStack{
   ...
}
.background(.ultraThinMaterial)

有關更多用法，請參閱文檔： https ://developer.apple.com/documentation/swiftui/material

Answer 5

我在清晰的背景中找到了針對閃爍問題的更清潔的解決方案。

struct ClearBackgroundView: UIViewRepresentable {
    func makeUIView(context: Context) -> UIView {
        return InnerView()
    }
    
    func updateUIView(_ uiView: UIView, context: Context) {
    }
    
    private class InnerView: UIView {
        override func didMoveToWindow() {
            super.didMoveToWindow()
            
            superview?.superview?.backgroundColor = .clear
        }
        
    }
}

用法

PresenterView()
    .fullScreenCover(isPresented: $isPresented) {
        PresentedView()
            .background(ClearBackgroundView())
    }