Pass Object details to another view [SwiftUI] - swiftui

Question

Facing problem to understand how to move Object details to another view using NavigationLink, I have read many articles and watched video, they all do the same as I do except for the Preview struct, they use local data and easily they map the view to the first item of the data like data[0]. While in my case, I fetch the data online, hence the above way did not help me to overcome the issue with the Preview struct, ERROR: Missing argument for parameter
Articles have been read:
developer.apple.com/tutorials/swiftui/building-lists-and-navigation
www.raywenderlich.com/5824937-swiftui-tutorial-navigation
www.youtube.com/watch?v=BCSP_uh0co0&ab_channel=azamsharp
/// Main View Code:
import SwiftUI
import SDWebImageSwiftUI
struct HomeView: View {
#State var posts: [Posts] = []
#State var intPageNo: Int = 0
var body: some View {
NavigationView {
List(posts) {post in
NavigationLink(destination: ViewPostView(post: post)){
VStack{
HStack{
WebImage(url: URL(string: post.featured_image))
.resizable()
.placeholder(Image("logo"))
.frame(width: 150, height: 150, alignment: .center)
VStack(alignment: .leading, spacing: 10.0){
Text("By: \(post.author_name)")
Text("Since: \(post.since)")
Text("City: \(post.city_name)")
Text("Category: \(post.category_name)")
}
.font(.footnote)
Spacer()
}
Text(post.title)
.font(.body)
.fontWeight(.bold)
.frame(alignment: .trailing)
.flipsForRightToLeftLayoutDirection(true)
}
}
}
.onAppear{
self.intPageNo += 1
ApiPosts().getPosts(intPage: self.intPageNo){(posts) in
self.posts = posts
}
}
.navigationBarTitle(Text("Home"))
}
}
}
struct HomeView_Previews: PreviewProvider {
static var previews: some View {
HomeView()
}
}
/// Detail View Code:
import SwiftUI
struct ViewPostView: View {
#State var comments: [Comments] = []
#State var post: Posts
var body: some View {
NavigationView {
VStack{
Text(post.post_content)
.frame(alignment: .trailing)
List(comments){comment in
VStack(alignment: .trailing, spacing: 10){
HStack(spacing: 40){
Text(comment.author_name)
Text(comment.comment_date)
}
Text(comment.comment_content)
}
}
.frame(alignment: .trailing)
.onAppear {
PostViewManager().getComments(intPostID: self.post.id){(comments) in
self.comments = comments
}
}
}
}
}
}
struct ViewPostView_Previews: PreviewProvider {
static var previews: some View {
ViewPostView()
}
}
/// Fetching data Code:
struct Comments: Codable, Identifiable {
var id: Int
var author_name: String
var comment_content: String
var comment_date: String
var comment_date_gmt: String
var approved: String
}
class PostViewManager {
func getComments(intPostID: Int, completion: #escaping ([Comments]) -> ()){
guard let url = URL(string: "https://test.matjri.com/wp-json/matjri/v1/comments/\(intPostID)") else {return}
URLSession.shared.dataTask(with: url) { (data, _, _) in
let comments = try! JSONDecoder().decode([Comments].self, from: data!)
DispatchQueue.main.async {
completion(comments)
}
}
.resume()
}
}
struct Posts: Codable, Identifiable {
var id: Int
var title: String
var city_id: Int
var city_name: String
var category_id: Int
var category_name: String
var since: String
var author_id: String
var author_name: String
var post_content: String
var featured_image: String
}
class ApiPosts {
func getPosts(intPage: Int, completion: #escaping ([Posts]) -> ()){
guard let url = URL(string: "https://test.matjri.com/wp-json/matjri/v1/posts/0") else {return}
URLSession.shared.dataTask(with: url) { (data, _, _) in
let posts = try! JSONDecoder().decode([Posts].self, from: data!)
DispatchQueue.main.async {
completion(posts)
}
}
.resume()
}
}

Answer 1

The error you get "Preview struct, ERROR: Missing argument for parameter", typically is because you did not provide the required parameters to the Preview.
ViewPostView expect to be passed "var post: Posts", so in ViewPostView_Previews you
need to provide that, for example:
struct ViewPostView_Previews: PreviewProvider {
static var previews: some View {
ViewPostView(post: Posts(id: 1, title: "title", ... ))
}
}