Style group item

Sources/UIPreview/UICatalog/CatalogItem.swift

@@ -1,6 +1,7 @@
 #if canImport(SwiftUI)
 import SwiftUI
 #endif
+import UIKit
 
 @available(iOS 13, *)
 struct CatalogItem<Content: UIViewCatalogPresentable>: View {
@@ -22,12 +23,35 @@ struct CatalogItem<Content: UIViewCatalogPresentable>: View {
         .fontWeight(.bold)
       Content.preview(with: model)
         .frame(maxWidth: .infinity)
-//        .previewLayout(.sizeThatFits)
         .background(Color(.systemBackground))
         .colorScheme(scheme)
       Divider()
-
+        .background(Color.secondary)
     }
     .padding()
   }
 }
+
+#if DEBUG
+@available(iOS 13, *)
+struct CatalogItem_Previews: PreviewProvider {
+  static var previews: some View {
+    NavigationView {
+      ScrollView {
+        CatalogItem<TestView>(configuration: .init())
+      }.navigationBarTitle("TestView")
+    }
+  }
+}
+
+private final class TestView: UILabel, UICatalogPresentable {
+  static var previewModels = [
+    "Hello world",
+    "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum"
+  ]
+
+  func apply(previewModel: String) {
+    text = previewModel
+  }
+}
+#endif

Sources/UIPreview/UICatalog/GroupItem.swift

@@ -4,25 +4,58 @@ import SwiftUI
 
 @available(iOS 13, *)
 struct GroupItem: View {
-  typealias Element = (title: String, builder: () -> AnyView)
+  struct Model: Identifiable {
+    let id = UUID().uuidString
+    var isExpanded = false
+    let title: String
+    let content: () -> AnyView
+  }
 
-  let items: [Element]
+  let items: [Model]
+
+  var body: some View {
+    ForEach(items) { item in
+      GroupItemRow(model: item).buttonStyle(PlainButtonStyle())
+    }
+  }
+}
+
+
+@available(iOS 13, *)
+struct GroupItemRow: View {
+
+  @State var model: GroupItem.Model
 
   var body: some View {
     VStack {
-      ForEach(items, id: \.title) { item in
-        Group {
-          Text(item.title)
+      Button(action: {
+        model.isExpanded.toggle()
+      }, label: {
+        HStack {
+          Text(model.title)
             .font(.headline)
             .fontWeight(.bold)
-          Divider()
-          item.builder()
+          if model.isExpanded {
+            Image(systemName: "chevron.up")
+          } else {
+            Image(systemName: "chevron.down")
+          }
+        }
+        .offset(x: 10)
         .frame(maxWidth: .infinity)
-        }
-      }.padding(.bottom, 10)
+        .padding()
+        .background(Color.secondary)
+        .cornerRadius(8)
+      })
+      if model.isExpanded {
+        model.content()
+          .frame(maxWidth: .infinity)
+          .padding([.top, .bottom], /*@START_MENU_TOKEN@*/10/*@END_MENU_TOKEN@*/)
       }
     }
   }
+}
+
 
 #if DEBUG
 @available(iOS 13, *)
@@ -30,8 +63,10 @@ struct GroupItem_Previews: PreviewProvider {
   static var previews: some View {
     ScrollView {
       GroupItem(items: [
-        ("Group 1", { AnyView(Text("Preview")) } ),
-        ("Group 2", { AnyView(Image(systemName: "square.and.pencil")) } )
+        .init(title: "Group 1",
+              content: { AnyView(Text("Preview")) } ),
+        .init(title: "Group 2",
+              content: { AnyView(Image(systemName: "square.and.pencil")) } )
       ])
     }
   }

Sources/UIPreview/UICatalog/PreviewDescriptor.swift

@@ -43,7 +43,7 @@ public extension UICatalog.PreviewDescriptor {
        title: String? = nil) {
     id = content.map(\.id).joined()
     self.title = title ?? content.map(\.title).joined(separator: " ")
-    let items: [GroupItem.Element] = content.map {  ($0.title, $0.builder) }
+    let items = content.map { GroupItem.Model(title: $0.title, content: $0.builder) }
     builder = { AnyView(GroupItem(items: items)) }
   }
 }