How to remove padding on left and right of list in SwiftUI [duplicate]

Update

Take a look at this answer

It looks like .listRowInsets doesn't work for rows in a List that is initialised with content

So you can do this if you change your code slightly. First you need to remove the padding from the post view so the text will go to the edge (if that's what you want):

struct PostView: View {
  let placeholder = UIImage(named: "arianaGrande")!
  var post: Post

  var body: some View {
    VStack {
      HStack {
        Text(post.album).font(.title)
        Spacer()
        Text(post.artist)
      }// .padding() -- This padding adds space before "Sweetener and after Ariana Grande

      Image(uiImage: placeholder)
        .resizable()
        .aspectRatio(placeholder.size,  contentMode: .fit)
      HStack {
        Image("plus-icon")
        Spacer()
        Image("comment-icon")
        Spacer()
        Image("headset-icon")
      }.padding()

      HStack {
        Text(post.username)
        Spacer()
        Text(post.textContent)
      }//.padding() -- Same thing here.
    }
  }
}

struct PostView_Previews: PreviewProvider {
  static var previews: some View {
    PostView(post: Post(
      artist: "Ariana Grande",
      album: "Sweetener",
      albumArtUrl: "",
      username: "DoesData",
      textContent: "Text Content"
      )
    )
  }
} 

Then you can initialize your list slightly differently to remove the spacing.

struct PostsView: View {
  var posts = [
    Post(
      artist: "Ariana Grande",
      album: "Sweetener",
      albumArtUrl: "",
      username: "DoesData",
      textContent: "Text Content"
    )
  ]

  var body: some View {
    List {
      ForEach(posts) { post in
        PostView(post: post)
          .listRowInsets(EdgeInsets())
      }
    }
  }
}

struct Post: Identifiable {
  let id = UUID()
  let artist: String
  let album: String
  let albumArtUrl: String
  let username: String
  let textContent: String
}

struct PostsView_Previews: PreviewProvider {
  static var previews: some View {
    PostsView()
  }
}

Result:

Original Answer

It looks like you can adjust padding on the list itself to remove the leading and trailing margins.

import SwiftUI

struct PostsView: View {
   @ObservedObject var fbVM = FirebaseInfo()

    var body: some View {

       List(fbVM.visiblePosts) { post in
            PostView(post: post)
       }.padding(.horizontal, -20) // -20 seems to make it go edge to edge

    }
}

struct PostsView_Previews: PreviewProvider {
    static var previews: some View {
        PostsView()
    }
}

You also might need to adjust the padding inside PostView for the text like this Text("Title").font(.title).padding(.leading, -10) This seems more elaborate than it should be, but it appears to work.

There are several spacings that you can change in a list. Take a look at this color-coded map and pick the one that fits your needs:

List(1...100, id: \.self) { item in
    Text("\(item)")
        .padding() // 🟣 comment to remove PURPLE padding
        .background(Color.yellow)
        // .listRowInsets(EdgeInsets()) // 🔵 uncomment to remove BLUE inset
}
// .listStyle(.plain) // 🟢 uncomment to remove GREEN inset
// .listStyle(.grouped) // 🔴 uncomment to remove RED inset

_RTL-Demo

Important note:

It looks like .listRowInsets doesn't work for rows in a List that is initialized with content. So you need to use ForEach inside the list like:

var body: some View {
    List {
        ForEach(...) {
            Text("String")
                .listRowInsets(EdgeInsets())
        }
    }
}