我想在foreach内部的模型中传递一个数组的范围。
我重新创建了一个示例：
import SwiftUI
class TheModel: ObservableObject {
@Published var list: [Int] = [1,2,3,4,5,6,7,8,9,10]
}
struct MainView: View {
@StateObject var model = TheModel()
var body: some View {
VStack {
ForEach (0...1, id:\.self) { item in
SubView(subList: $model.list[0..<5]) <-- error if I put a range
}
}
}
}
struct SubView: View {
@Binding var subList: [Int]
var body: some View {
HStack {
ForEach (subList, id:\.self) { item in
Text("\(item)")
}
}
}
}
struct MainView_Previews: PreviewProvider {
static var previews: some View {
MainView()
}
}
周围的工作
我发现是传递所有的列表，并在子视图内部执行范围。但我不想这样做,因为数组非常大：
struct MainView: View {
@StateObject var model = TheModel()
var body: some View {
VStack {
ForEach (0...1, id:\.self) { i in
SubView(subList: $model.list, number: i, dimension: 5)
}
}
}
}
struct SubView: View {
@Binding var subList: [Int]
var number: Int
var dimension: Int
var body: some View {
HStack {
ForEach (subList[number*dimension..<dimension*(number+1)].indices, id:\.self) { idx in
Button(action: {
subList[idx] += 1
print(subList)
}, label: {
Text("num: \(subList[idx])")
})
}
}
}
}
我会将模型传递给子视图，因为它是一个类，并且将通过引用传递，然后将范围作为单独的参数传递。
这是我对SubView的新实现
struct SubView: View {
var model: TheModel
var range: Range<Int>
var body: some View {
HStack {
ForEach (model.list[range].indices, id:\.self) { idx in
HStack {
Button(action: {
model.list[idx] += 1
print(model.list)
}, label: {
Text("num: \(model.list[idx])")
})
}
}
}
}
}
注意，我向foreach头添加了indexs以确保使用索引而不是数组中的值访问数组。
调用视图将如下所示
var body: some View {
VStack {
SubView(model: model, range: (0..<5))
Text("\(model.list.map(String.init).joined(separator: "-"))")
}
额外的文本只是用于测试目的
