SwiftUI 无法删除选择器上方的空间 - 表单版本

Question

SwiftUI Can't Remove Space Above Picker - Form Version

I'm struggling mightily with the formatting of pickers in SwiftUI. I built a simple picker with a few other views in a single view app. There is a space between the Header and the picker that I can't remove. I'd settle for setting the gray color to white. If I change the frame of the picker it just scrunches the picker - the gray space remains untouched. I'm not sure what to even call that space - it does not appear to be part of the Header, nor the Picker, nor the Form nor the Section.

The only reference to this issue that I found was article 57851878 which suggests putting the view in the header itself. That does not work and would be a really bad idea anyway.

The space in the image outlined is red is the subject:

And this is the code:

struct ContentView: View {

    @State private var thing: String = ""
    @State private var enableSaveButton = false
    @State private var selection = 0
    @State private var selection2 = 0

    var things = ["books","desks","chairs","lamps","couches","shelves"]

    var body: some View {
        NavigationView {
            //ScrollView{
            VStack {
                Group {//first group
                    VStack {
                        Text("Text at the Top")
                        TextField("enter something here", text: $thing)
                            .frame(width:350, height: 50)
                            .clipShape(RoundedRectangle(cornerRadius: 12))
                            .overlay(RoundedRectangle(cornerRadius: 12)
                            .stroke(Color.gray, lineWidth: 2))
                            .padding(.leading, 5)
                            .padding(.bottom, 20)

                        Section(header: HStack {
                            Text("This is the Header")
                                .font(.headline)
                                .foregroundColor(.blue)
                                .padding(.bottom, 0)
                                .padding(.leading, 30)
                            Spacer()
                        }
                        .background(Color.white)
                        .listRowInsets(EdgeInsets(
                            top: 0,
                            leading: 0,
                            bottom: 0,
                            trailing: 0))
                        ) {

                            Form {
                                Text("This is the Chosen Thing: \(self.things[selection2])")

                                Picker(selection: self.$selection2, label: Text("Choose Thing").foregroundColor(.blue)) {
                                    ForEach(0 ..< things.count) {
                                        Text(self.things[$0])
                                    }
                                }//picker
                            }//form
                                .frame(width:350, height: 115)
                                .padding(.top, 0)
                        }//first picker section
                    }//vstack
                }//first group

                Spacer()

                Group {//second Group
                    Text("Enable and Disable this button")
                    Button(action: {
                        print("whatever")
                    } ) {
                        ZStack {
                            RoundedRectangle(cornerRadius: 20)
                                .fill(Color.yellow)
                                .frame(width: 100, height: 40)
                            Text("Save").font(.headline)
                        }
                    }
                    .shadow(radius: 12, x: 10, y: 10)
                    //.disabled(!enableSaveButton)
                }//second Group
            }//outer VStack
                //}//Scrollview
                .navigationBarTitle("Things")
        }//nav view
    }//body
}

Any guidance would be appreciated.  Xcode 11.2.1 (11B500)

Answer 1

You can remove upper and lower space of Form by adding below code

struct ContentView: View {

    init() {
         UITableView.appearance().tableHeaderView = UIView(frame: CGRect(x: 0, y: 0, width: 0, height: Double.leastNonzeroMagnitude))
         UITableView.appearance().tableFooterView = UIView(frame: CGRect(x: 0, y: 0, width: 0, height: Double.leastNonzeroMagnitude))
    }

  //your code .....
}

Answer 2

Another possibility is to set the background color for the table view and table view cell to clear in init()

Init() {
    UiTableView.appearance().backgroundColor = .clear
    UITableViewCell.appearance().backgroundcolor = .clear
}

This will not get rid of the space, but it will make the underlying table transparent to the window background color

Answer 3

it looks like it is a section header of the form...

if you change your code like this you will see, you have a section header text. Why SwiftUI does this by itself ...i don't know....unfortunately it even does not disappear with frame set to height 0....

Form {
    Section(header: Text("General Settings")){
    Text("This is the Chosen Thing: \(self.things[selection2])")
    }

    Picker(selection: self.$selection2, label: Text("Choose Thing").foregroundColor(.blue)) {
        ForEach(0 ..< things.count) {
          Text(self.things[$0])
        }
    }//picker
}//form
   .frame(width:350, height: 115)
   .padding(.top, 0)