如何在 SwiftUI 中使用列表

Question

我有一个 WorkoutView，错误发生在 'List(workouts, id: .id)' 错误是 "Type '_' has no member 'id'" 这是视图：

struct WorkoutsView: View {
@State var presentBuilder = false
var workouts = WorkoutData.data()

var body: some View {
    NavigationView {
        List(workouts, id: \.id) { workout in
            NavigationLink(destination: WorkoutDetailView()) {
                WorkoutBlockView(name: workout.name, workoutLength: workout.length, amountCompleted: workout.completed())
            }
        }
        .navigationBarItems(leading:
            Button(action: {
                self.presentBuilder.toggle()
            }, label: {
                ZStack {
                    Circle()
                        .foregroundColor(.blue)
                        .frame(width: 30, height: 30)
                        .shadow(radius: 7.0)
                    Image("add")
                        .foregroundColor(.black)
                }
            })
        )
    }.sheet(isPresented: $presentBuilder) {WorkoutBuilderView()}

}

}

这里是 WorkoutData/Workout:

struct WorkoutData {
static func data() -> [Workout] {
    return [Workout(length: 17, name: "Example Workout", description: "workout description"), Workout(length: 17, name: "Example Workout", description: "workout description")]
}
}

struct Workout {
let id = UUID()
var progress = 1
var length: Int
var name: String
var description: String

func completed() -> Int {
    return progress - 1
}

如果我没理解错的话，List 无法确定锻炼的类型，因此找不到 id。也许我需要让 Workout 符合 Identifiable（试过这个）？谢谢！

Answer 1

我正在研究类似的 SwiftUI 原型。我使用的是 HStack，但我认为您可以通过枚举 class Hashable 来做到这一点。

struct Statistic: Hashable {
    let title, stat: String
}
// ... 
let boxes: [Statistic]
// ... 
ScrollView(.horizontal, showsIndicators: false) {
    HStack {
        ForEach(boxes, id: \.self) { box in
            BoxView(box: box)

        }
    }
}

在你的情况下，我认为你会让 Workout 可散列

struct Workout: Hashable {
    let id = UUID()
    var progress = 1
    var length: Int
    var name: String
    var description: String

    func completed() -> Int {
        return progress - 1
    }
}

并使用 self 而不是 id

List(workouts, id: \.self) { workout in

Answer 2

与您的（“.id”）无关。这样的List错误是因为ViewBuilder里面的一些View不正确。

如果我替换

 1. WorkoutDetailView()) 
 2. WorkoutBlockView(name: workout.name, workoutLength: workout.length, amountCompleted: workout.completed())
 3. WorkoutBuilderView()

和 Text，左侧的 WorkoutsView 布局是可行的。所以，你得弄清楚为什么那些视图会出现一些问题。

    struct WorkoutsView: View {
   @State var presentBuilder = false
    var workouts = WorkoutData.data()

 var body: some View {
   NavigationView {
    List(workouts, id: \.id) { workout in
        NavigationLink(destination: Text("placeHolder")) {
            Text("placeHolder")
        }
    }
    .navigationBarItems(leading:
        Button(action: {
            self.presentBuilder.toggle()
        }, label: {
            ZStack {
                Circle()
                    .foregroundColor(.blue)
                    .frame(width: 30, height: 30)
                    .shadow(radius: 7.0)
                Image("add")
                    .foregroundColor(.black)
            }
        })
    )
   }.sheet(isPresented: $presentBuilder) {Text("placeHolder")}

 }

 }

希望对您有所帮助。

如何在 SwiftUI 中使用列表

How to use a List in SwiftUI

arrays

list

swift

swift5

swiftui