swift - 当变量嵌套在对象中时，如何使用 SwiftUI 将绑定(bind)传递给 subview ？

Question

这行得通

import SwiftUI
struct ContentView : View {
    @State var val1: Int = 0
    var body: some View {
        MySubview(val1: $val1)
    }
}

#if DEBUG
struct ContentView_Previews : PreviewProvider {
    static var previews: some View {
        ContentView(val1: 0)
    }
}
#endif

struct MySubview : View {
    @Binding var val1: Int
    var body: some View {
        return Text("Value = \(val1)")
    }
}

但是当变量嵌套在对象中时，这会失败

import SwiftUI
struct MyStruct {
    let number: Int
}

struct ContentView : View {
    @State var val1 = MyStruct(number: 7)
    var body: some View {
        MySubview(val1: $val1.number)
    }
}

#if DEBUG
struct ContentView_Previews : PreviewProvider {
    static var previews: some View {
        ContentView(val1: 0)
    }
}
#endif

struct MySubview : View {
    @Binding var val1: Int
    var body: some View {
        return Text("Value = \(val1)")
    }
}

显示的错误:无法推断通用参数“Subject”

如何将嵌套变量作为绑定(bind)传递给 subview ？

Answer 1

这个错误非常具有误导性。数字必须是 var，而不是 let:

struct MyStruct {
    var number: Int
}

更改它，它将正常工作。