SwiftUI:以编程方式为 Picker 设置值

SwiftUI: Programmatically setting value for Picker

Internet 上的所有示例都显示了以下类型的用于实现选择器的代码:

struct MyView: View 
{
   var colours = ["Red", "Green", "Blue"]
   @State private var myColourIndex = 1
   @State private var myColour = "Green"
   var body: some View 
   {
       VStack 
       {
           Picker(selection: $myColourIndex, label: Text("Choose a colour")) 
           {
               ForEach(0 ..< colours.count) 
               {
                   Text(self.colours[[=10=]])
               }
           }
       }
   }
}

这可能很明显,但我的问题是如何根据存储在 myColour 中的字符串值而不是索引来设置部分?

实际上,几乎相同(测试并适用于 Xcode 11.2 / iOS 13.2):

struct MyView: View
{
   var colours = ["Red", "Green", "Blue"]
   @State private var myColourIndex = 1
   @State private var myColour = "Green"

   var body: some View {
       VStack {
           Picker("Choose a colour", selection: $myColour) {
               ForEach(colours, id: \.self) { colour in
                   Text(colour)
               }
           }
       }
   }
}