为什么swiftui中的导航视图栏那么大

import SwiftUI
struct SecondView: View {

var ResearchMCQ: Question


//Creating Variables for Revision Topics
@State private var setOptionOne = false
@State private var setOptionTwo = false
@State private var setOptionThree = false
    
//User Home Page View
        var body: some View {
            
//Allows for Navigation and Scrolling
        NavigationView {
        ScrollView{
            
//App Logo and Vertical Stacks
            VStack(spacing: 1.0) {
            Image("AppLogo")
                    .resizable()
                    .scaledToFit()
                    .padding(.trailing, 50.0)
                .frame(height: 100, alignment: .topLeading)

    Spacer()
    Spacer()
                
//Multiple Choice Question Appears
    Group {
    Text(ResearchMCQ.question)
    .padding(.trailing, 4)
    
    Spacer()
    Spacer()
        
//Ensures Only One Answer Can Be Selected
        let OptionOne = Binding<Bool>(get: { self.setOptionOne }, set: { self.setOptionOne = $0; self.setOptionTwo = false; self.setOptionThree = false })
        let OptionTwo = Binding<Bool>(get: { self.setOptionTwo }, set: { self.setOptionOne = false; self.setOptionTwo = $0; self.setOptionThree = false })
        let OptionThree = Binding<Bool>(get: { self.setOptionThree }, set: { self.setOptionOne = false; self.setOptionTwo = false; self.setOptionThree = $0 })

//Shows User MCQ Options
        VStack {
            Toggle(ResearchMCQ.options[0], isOn: OptionOne)
                .toggleStyle(.button)
                .tint(Color(.gray))
                .foregroundColor(Color("Black-White"))
            Toggle(ResearchMCQ.options[1], isOn: OptionTwo)
                .toggleStyle(.button)
                .tint(Color(.gray))
                .foregroundColor(Color("Black-White"))
            Toggle(ResearchMCQ.options[2], isOn: OptionThree)
                .toggleStyle(.button)
                .tint(Color(.gray))
                .foregroundColor(Color("Black-White"))
                 }
    }
                
                
        }
            
           // .padding(.top, -150)
    }
}
            
//Allows Navigation Through Pages
   .navigationTitle("")
    .padding(.top, -100)
            
        }

}

Shows large navigation bar

我试图创建一个导航栏，但是我希望它是空的，因此代码中有空的引号标记.当我像图中所示向上滚动时，导航栏占据了页面的很大一部分，你知道如何使它变小吗.作为第一次使用swift的程序员，任何帮助都将不胜感激！！！