SwiftUI-根据输入参数更改视图变量

如何根据调用视图时提供的输入参数categorySize更改视图中的@State变量大小

我想在categorySize=.Large时将大小更改为140，在categorySize=.Small时将大小更改为40

enum ExampleEnum {
     case Large
     case Small
}

struct TestView: View {

   let categorySize: ExampleEnum
   @State private var size: CGFloat = 92

   var body: some View {
   Image(name: "TestImage")
      .resizable()
      .frame(width: size, height: size)
   }
}

TestView(categorySize: .Small)

我尝试通过if语句执行此操作，但没有成功：

struct TestView: View {

   let categorySize: ExampleEnum
   @State private var size: CGFloat = 92

   var body: some View {

   if categorySize == .Large {      <=== Not working
      $size = 140
   } else if categorySize == .Small {
      $size = 40
   }

   Image(name: "TestImage")
      .resizable()
      .frame(width: size, height: size)
   }
}

struct TestView:View{
让类别化：ExampleEnum
@国家私有变量大小：CGFloat=92
var body：一些观点{
如果categorySize=.Large{这里是可能的方法

struct TestView: View {

    let categorySize: ExampleEnum

    var body: some View {

        var size: CGFloat  = 92
        if categorySize == .Large {
            size = 140
        } else if categorySize == .Small {
            size = 40
        }

        return Image(name: "TestImage")
            .resizable()
            .frame(width: size, height: size)
    }
}