SwiftUI retuning List or NavigationView in body: difference of return List and List in body-CodePudding

I have question about returning NavigationView and List inside of SwiftUI body

There are code snippets like this:

    var body: some View {
      let trailingItem = HStack {
        Button(action: { print("Button 1") }) {
          Image(systemName: "bell")
        }
        Button(action: { print("Button 2") }) {
          Image(systemName: "square.and.arrow.up")
        }
      }
      
      return NavigationView {
        Image("SwiftUI")
          .navigationBarItems(trailing: trailingItem)
          .navigationBarTitle("Title")
      }
    }

and this

    var body: some View {
      let numbers = [1, 2, 3, 4, 5]

      return List(numbers, id: \.self) {
        Text("\(String(describing: $0))")
      }
    }

In these two code snippets, I can find return keyword for NavigationView and List To figure out what does that grammar do, I tried deleting return keyword but nothing happened

I want to know: What does that return keyword do?

What is difference between using return for NavigationView and List

Thanks in advance for any help you are able to provide.

CodePudding user response：

Some of the features in SwiftUI's syntax are made possible by something called a View Builder which is a type of Result Builder

When using a View Builder, functions and computed properties have an implicit return (ie the last statement is returned even without the return keyword). There are also other specific rules about what kinds of implicit code can be included in a View Builder, but let declarations like your examples contain are fine. See https://swiftwithmajid.com/2019/12/18/the-power-of-viewbuilder-in-swiftui/ and https://swiftontap.com/viewbuilder for more information.

SwiftUI Views are an interesting special case because the var body property of the View is interpreted to be a ViewBuilder even though we don't have to explicitly annotate it with @ViewBuilder. However, if you were to try the same thing in a regular function, you would need to use that @ViewBuilder to get a similar result if the function had more than one statement (one-line functions in Swift have implicit returns as well).

@ViewBuilder func myView() -> some View {
    Text("test")
    Text("Another item")
}

So, in your code examples (since you were in var body), there is no difference between using return and omitting it.