SwiftUI - 使用枚举查看不更新

Question

首先，我想说的是值更新，因为我在控制台中打印值，并且确定，点击每个选项都会按预期打印。但是，出于 UI 目的，我添加了一些视觉组件/样式来帮助指示当前选择。

我的枚举：

enum Gender : Int, CaseIterable {
    case men = 0
    case women = 1
  

    private var cases: [String]  {
        ["Men", "Women"]
    }
   
    func toString() -> String {
        cases[self.rawValue]
    }
}

这是有助于显示数据和索引数据的逻辑的视图

struct GenderTabMenuIndicator: View {
    var category: Gender
    var body: some View {
        HStack {
            ForEach(0..<Gender.allCases.count) { cat in
                GenderTabMenuIndicatorItem(category: Gender.allCases[cat], isActive: Gender.allCases[cat] == category)
                
            }
        }.frame(width: UIScreen.main.bounds.width * 0.75)
    }
}

这只是视图。但是，isActive 似乎并没有从初始选择/值切换。

struct GenderTabMenuIndicatorItem: View {
    @State var category: Gender
    @State var isActive: Bool
    var body: some View {
        VStack(spacing: 0) {
            Text(category.toString().uppercased())
                .onTapGesture {
                    print("tapped")
                    print(category.toString())
                }
                .font(.system(size: 18, weight: isActive ? .bold : .light))
                .frame(maxWidth: .infinity)
                .layoutPriority(1)
            if isActive {
                Rectangle()
                    .frame(width: 50, height: 2, alignment: .center)

            }
        }.foregroundColor(Color(SYSTEM_FONT_COLOUR))
    }
}

这就是我在实际视图中声明/使用所有这些组件的方式：

@State private var selected_tab: Gender = .men

VStack {
GenderTabMenuIndicator(category: selected_tab)
}

我不知道它是否是 ForEach 循环，但它同时打印了通过的相应案例。我在可以更新视图的地方使用了@State，但没有成功。

任何帮助将不胜感激！

Answer 1

• @State 用于private更改，内部有视图

• 要从子视图来回更新更改，您必须使用@Binding

• 我们可以使用$ 访问/传递@State 的绑定，ex :- $yourStateVariable

这里是固定答案，

struct ContentView: View {
        @State private var selected_tab: Gender = .men
        
        var body: some View {
            VStack {
                Text("Selected: \(selected_tab.toString())")
                GenderTabMenuIndicator(category: $selected_tab)
            }
        }
    }

    enum Gender : Int, CaseIterable {
        case men = 0
        case women = 1
        
        
        private var cases: [String]  {
            ["Men", "Women"]
        }
        
        func toString() -> String {
            cases[self.rawValue]
        }
    }
    
    struct GenderTabMenuIndicator: View {
        @Binding var category: Gender
        var body: some View {
            HStack {
                ForEach(0..<Gender.allCases.count) { cat in
                    GenderTabMenuIndicatorItem(category: Gender.allCases[cat], selection: $category)
                    
                }
            }.frame(width: UIScreen.main.bounds.width * 0.75)
        }
    }
    
    struct GenderTabMenuIndicatorItem: View {
        var category: Gender
        @Binding var selection: Gender
        var body: some View {
            VStack(spacing: 0) {
                Text(category.toString().uppercased())
                    .onTapGesture {
                        selection = category
                    }
                    .font(.system(size: 18, weight: selection == category ? .bold : .light))
                    .frame(maxWidth: .infinity)
                    .layoutPriority(1)
                if selection == category {
                    Rectangle()
                        .frame(width: 50, height: 2, alignment: .center)
                    
                }
            }
        }
    }