SwiftUI ViewModifier vs ViewBuilder

https://vinsol.com/blog/2020/07/02/understanding-swiftuis-viewmodifiers-and-viewbuilders/ 

摘要：

ViewModifier:

1. 大多數 SwiftUI 的 View function 都是 View Modifier。Ex: font(), foregroundColor()
2. view Modifier 是 SwiftUI 中最常用來 modify View 的方式，用來產生客製化 Custom container View
3. Example:
   
   struct MyViewModifier: ViewModifier {
       private let ctaThemeColor = Color.blue
       func body(content: Content) -> some View {
           content
               .foregroundColor(.white)
               .padding()
               .background(ctaThemeColor)
               .clipShape(Capsule())
       }
   }
   使用：
   Text("Hello World") .modifier(MyViewModifier()) 

 ViewBuilder: 

1. 一直需要重複使用到的Base View，創造一個自己的 View Container，類似 VStack(), HStack()
2.  Example:
   
   struct MyContainerView<Content: View>: View {
       let content: Content
       init(@ViewBuilder content: () -> Content) {
           self.content = content()
       }

   var body: some View {

           ZStack {

               Color.yellow.edgesIgnoringSafeArea(.all)

               HStack {

                   Spacer()

                   VStack {

                       Text("DemoApp")

                           .foregroundColor(.purple)

                           .font(.system(size: 15, weight: .bold))

                           .padding(.trailing, 15)

                       Spacer()

                   }

               }

               content

           }

       }

   }
    使用：
   
   struct DemoAppView: View {
       var body: some View {
           MyContainerView {
               Text("I ❤️ SwiftUI") // The main content
           }
       }
   }