SwiftUI Sheet中.ultraThinMaterial背景随机失效问题求助

问题场景 #

开发参考Apple Maps的SwiftUI应用时，首页主Sheet设置了.ultraThinMaterial背景，多数情况下显示正常，但打开CarDetailsSheet时，主Sheet背景会随机失效，变为白色。

相关代码 #

主Sheet展示代码 #

.sheet(isPresented: .constant(true)) {
    BottomSheet()
        .presentationDetents([.medium, .large, .height(geometry.safeAreaInsets.bottom + 32)])
        .presentationBackgroundInteraction(.enabled)
        .presentationBackground(.ultraThinMaterial)
        .interactiveDismissDisabled()
}

BottomSheet相关代码 #

struct BottomSheet: View {
    // ...（省略部分代码）

    // 详情Sheet展示
    .sheet(item: $selectedCar) { car in
        VStack {
            Spacer()
            CarDetailsSheet(car.id)
                .padding()
                .presentationBackground(.ultraThinMaterial)
        }
    }

    // ...（省略部分代码）
}

已尝试操作 #

调整修饰符顺序、移除多余背景修饰符，问题仍未解决：打开CarDetailsSheet时，背景有时显示正常的.ultraThinMaterial，有时变为白色。

视觉对比 #

• 预期背景：
• 实际异常背景：

关闭CarDetailsSheet时的日志 #

Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. 
    Try this: 
        (1) look at each constraint and try to figure out which you don't expect; 
        (2) find the code that added the unwanted constraint or constraints and fix it. 
(
    "<NSLayoutConstraint:0x2838ed3b0 'accessoryView.bottom' _UIRemoteKeyboardPlaceholderView:0x131448960.bottom == _UIKBCompatInputView:0x13d61f7c0.top   (active)>",
    "<NSLayoutConstraint:0x28383d9a0 'assistantHeight' SystemInputAssistantView.height == 45   (active, names: SystemInputAssistantView:0x13d61b0e0 )>",
    "<NSLayoutConstraint:0x2838c30c0 'assistantView.bottom' SystemInputAssistantView.bottom == _UIKBCompatInputView:0x13d61f7c0.top   (active, names: SystemInputAssistantView:0x13d61b0e0 )>",
    "<NSLayoutConstraint:0x2838c2bc0 'assistantView.top' V:[_UIRemoteKeyboardPlaceholderView:0x131448960]-(0)-[SystemInputAssistantView]   (active, names: SystemInputAssistantView:0x13d61b0e0 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x2838c2bc0 'assistantView.top' V:[_UIRemoteKeyboardPlaceholderView:0x131448960]-(0)-[SystemInputAssistantView]   (active, names: SystemInputAssistantView:0x13d61b0e0 )>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.

环境信息 #

• Xcode版本：15.1 (15C65)
• iOS版本：17.2

解决建议 #

• 优化嵌套Sheet布局层级：iOS 17的嵌套Sheet在处理presentationBackground时有随机渲染bug，先移除内层Sheet外层的VStack和Spacer，直接给CarDetailsSheet添加背景修饰符，减少布局层级干扰：

  .sheet(item: $selectedCar) { car in
      CarDetailsSheet(car.id)
          .padding()
          .presentationBackground(.ultraThinMaterial)
  }
  

• 强制主Sheet刷新：关闭内层Sheet后，通过更新主Sheet的id触发重新渲染，确保背景恢复：

  .sheet(isPresented: .constant(true)) {
      BottomSheet(selectedCar: $selectedCar)
          // 保留原有修饰符
          .id(selectedCar?.id ?? UUID())
  }
  

• 处理键盘约束冲突：日志中的约束问题和键盘占位视图相关，若CarDetailsSheet包含输入控件，在其消失时强制收起键盘，避免干扰布局：
  在CarDetailsSheet中添加：

  .onDisappear {
      UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder), to: nil, from: nil, for: nil)
  }
  

• 尝试系统版本调整：该问题大概率是iOS 17.2的系统bug，可升级到iOS 17.3及以上版本，或回退到iOS 17.1，验证问题是否解决。

内容的提问来源于stack exchange，提问作者raouf Mehdid