如何在 Swift 中从另一个结构中编辑一个结构中的数组？答案

【问题标题】：How to edit an array in one struct from another struct in Swift?如何在 Swift 中从另一个结构中编辑一个结构中的数组？
【发布时间】：2019-11-04 02:47:15
【问题描述】：

我在一个名为 WorkoutBuilderView 的结构中有一组“锻炼集”。我的问题是我需要从嵌套在 WorkoutBuilderView 中的结构访问该数组的内容（如下所示）。此结构不需要嵌套在 WorkoutBuilderView 中，但它是首选。我唯一真正需要的是能够从另一个结构编辑 sets 数组。

可能为结构创建“inout”类型的参数？（据我所知，这只适用于方法）

需要访问的数组称为sets。
需要访问的位置用注释标记 //access point

代码：

struct WorkoutBuilderView: View {


@State var sets = [WorkoutSet(id: 0, percentage: -1, repetitions: -1, alteredValue: .max)]

var body: some View {
    Background {
        Group {
            ...
            if self.sets.count > 0 {
                ScrollView {
                    ForEach(self.sets) { set in
                        WorkoutSetLayout(index: set.id) //where sets needs to be passed in
                    }
                }

            }
            ...
        }
    }
    }

//this is the struct where the array needs to be accessed
struct BuilderPicker: View {

    let name: String
    let options: Array<String>
    let setIndex: Int


    @State var selectedOption = 0
    var body: some View {
        HStack {
            ...
        }

        .onReceive([self.selectedOption].publisher.first()) { (value) in

            //change sets here
            //access point
            print(value)

        }
    }

}

//layout (sets needs to pass through here too)
struct WorkoutSetLayout: View {
    let index: Int
    var body: some View {
        VStack(alignment: .leading) {
            Text("Set \(index + 1)")
            ...
            //the array needs to go into the BuilderPicker where it will be edited
            BuilderPicker(name: "Weight % of", options: [AlteredValue.max.rawValue, AlteredValue.weight.rawValue], setIndex: index)
            ...
        }
    }
}
//you probably don't need to worry about the Background
struct Background<Content: View>: View {
    private var content: Content

    init(@ViewBuilder content: @escaping () -> Content) {
        self.content = content()
    }

    var body: some View {
        EmptyView()
            .frame(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)
            .overlay(content)
            .padding(.top, 75)
    }
}


}

【问题讨论】：

标签： swift struct scope swiftui inout

【解决方案1】：

如果我正确理解您的问题，@Binding 正是为此目的

1) 将绑定变量添加到嵌套结构中，如

//layout (sets needs to pass through here too)
struct WorkoutSetLayout: View {
    let index: Int
    @Binding var data: [WorkoutSet]
    ...

2) 通过初始化器将模型嵌套在父级中，如

ForEach(self.sets) { set in
    WorkoutSetLayout(index: set.id, data: self.$sets)
}

【讨论】：