SwiftUI: why can't I map views in a previews in PreviewProvider?

Question

I know that I can display several previews doing this:

struct TestView: View {
    let number: Int
    
    var body: some View {
        ZStack {
            Color.orange
            Text("\(number)")
                .fontWeight(.heavy)
                .font(.system(size: 56.0))
        }
        .frame(width: 100, height: 100, alignment: .center)
    }
}

struct TestView_Previews: PreviewProvider {
    static var previews: some View {
        TestView(number: 3)
        TestView(number: 5)
    }
}

But why can't I, instead, write this instead?

static var previews: some View {
    [3, 5].map { TestView(number: $0) }
}

(I'm getting this error: Return type of static property 'previews' requires that '[TestView]' conform to 'View')

Thank you for your help

Answer 1

[TestView], also known as Array<TestView>, does not conform to View.

SwiftUI's solution is the ForEach view:

static var previews: some View {
    ForEach([3, 5], id: \.self) {
        TestView(number: $0)
    }
}

Note that this assumes every element of the array is unique (which is true in this example).