swift - '? :'表达式中的结果值具有不匹配的类型 'some View'和 '...'

Question

当我尝试对navigationBarItems进行三元操作以获取各种 View 时，出现此错误:

Result values in '? :' expression have mismatching types 'some View' and 'ProfileImageBarButton'

@State var searchTapped: Bool = false

var body: some View {
    NavigationView {
        Text("lol")
            
   --> here i get the error .navigationBarItems(leading: searchTapped ? backButton : ProfileImageBarButton(showMenu: $showMenu))
        .navigationBarTitle(Text(""), displayMode: .inline)
    }.overlay(searchTextField)
}

private var backButton: some View {
    Image(systemName: "arrow.left")
        .foregroundColor(Color.blue)
        .onTapGesture {
            self.searchTapped = false
        }
}

这是 ProfileImageBarButton:

struct ProfileImageBarButton: View {
    @Binding var showMenu: Bool
    
    var body: some View {
        Image(uiImage: UserDefaults.standard.getProfileImage()!)
            .resizable()
            .renderingMode(.original)
            .frame(width: 30, height: 30)
            .clipShape(Circle())
            .onTapGesture {
                self.showMenu.toggle()
            }
    }
}

Answer 1

错误是在表达式中告诉您的:

condition ? true_result : false_result

true_result和 false_result都必须具有相同的类型。

有多种方法可以解决此问题，这里有两种:

.navigationBarItems(leading: searchTapped ? AnyView(backButton) : AnyView(ProfileImageBarButton(showMenu: $showMenu)))

或者

.navigationBarItems(leading: barItems())

...

func barItems() -> some View {
    return Group {
        if searchTapped {
            backButton
        } else {
            ProfileImageBarButton(showMenu: $showMenu)
        }
    }
}