"Missing Arguement for parameter 'navBarHidden' in call" Error

Question

Created Mar ’21

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Hi everyone! I am having difficulty with an error that I can't seem to solve. I've been trying to make my navigation bars from previous views hide. I finally found the code that I needed, but then I got this error. It is coming from the preview code at the bottom. It says that I need to change

Code Block happy()

to

Code Block happy(navBarHidden: <#Binding<Bool>#>)

But, when I do this, it gives me another error saying "Editor Placeholder in Source File" I know it wants me to replace this text with something, but I'm not sure what. Any suggestions?

Thank you very much!
Tyler Nichols

Code Block import SwiftUIimport Swift
struct happy: View {
  @State private var happy = ["chicken", "burgers", "roast beef"]
     
  @State private var editMode = EditMode.inactive
   
  @Binding var navBarHidden : Bool
   
  var body: some View {
    NavigationView {
      VStack{
        List {
          ForEach(happy, id: \.self) { good in
            Text(good)
          }
        }
        .navigationBarTitle("My Happy Food", displayMode: .inline)
        .onAppear() {
          self.navBarHidden = false
           
          }
        .navigationBarItems(leading: EditButton())
        .environment(\.editMode, $editMode)
        }
      }
    }
  }
struct Good_Previews: PreviewProvider {
  static var previews: some View {
    happy()
  }
}

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Answer 1

BabyJ OP

Mar ’21

happy requires that a Binding<Bool> be passed to it. There are two ways that I suggest you achieve this:

Firstly, you can use the constant static method to quickly show the view in the preview canvas in its different states just by changing the boolean value.

Code Block Swiftstruct Good_Previews: PreviewProvider {
	static var previews: some View {
		happy(navBarHidden: .constant(true))
	}
}

This is probably the preferred way for previewing and testing.

The other way is to just use a State property, changing that, and pass that binding to the view as normal.

Code Block Swiftstruct Good_Previews: PreviewProvider {
	@State static private var navBarHidden = true
	static var previews: some View {
		happy(navBarHidden: $navBarHidden)
	}
}

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