TabView blank when trying to display json data via onAppear() - swift

Question

I followed this tutorial to call data from my API. I veered off a bit and instead used TabView to show a "home page" where data loads in the first tab. It "works" in the sense that if I navigate to another tab and go back to the home tab the data appears. When I open the app though, the tab is blank. I initially declare posts as an empty array, by why is onAppear() not populating it?
Here's the view that is supposed to be displaying my data
struct DiscoverView: View {
#ObservedObject var discoverPosts: DiscoverPosts
var body: some View {
NavigationView{
ScrollView(.vertical, showsIndicators: false) {
VStack(alignment: .center){
ForEach(self.discoverPosts.posts) { post in
HStack{
DiscoverList(isModal : false,displayName : post.displayName,id : post.id,likes : post.likes,owner : post.owner,avatar : post.avatar,author_id : post.author_id,icebreaker : post.icebreaker,answer : post.answer,mediaLink : post.mediaLink,songURL : post.songURL,type : post.type,liked: post.liked)
}
.padding(10)
}
}
}
.onAppear(){
// self.discoverPosts.getPosts()
}
.navigationViewStyle(StackNavigationViewStyle())
.navigationBarTitle("Discover")
}
}
}
here is my discoverPosts()
class discoverPosts : ObservableObject {
#State var posts : [Post] = []
func getPosts(completion: #escaping ([Post]) -> ()){
let feedURL = "URL"
guard let url = URL(string: feedURL) else { return }
URLSession.shared.dataTask(with: url) { (data, _, _) in
let posts = try! JSONDecoder().decode([Post].self, from: data!)
DispatchQueue.main.async {
self.posts = posts
completion(posts)
}
}
.resume()
}
}
my ConventView.swift that shows the TabView. I believe the issue could be the hierarchy
struct ContentView: View {
var body: some View {
Home()
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
struct Home : View {
#State var show = false
#State var status = UserDefaults.standard.value(forKey: "status") as? Bool ?? false
var body: some View{
VStack{
if self.status{
TabView {
DiscoverView(discoverPosts: DiscoverPosts())
.tabItem(){
Image(systemName: "person")
.font(.system(size:20))
}
.tag(1)
InboxView(offsetLine: IndexSet.Element())
.tabItem(){
Image(systemName: "message")
.font(.system(size: 20))
}
.tag(2)
ProfileView()
.tabItem(){
Image(systemName: "person")
.font(.system(size: 20))
}
.tag(3)
}
.accentColor(Color.purple)
.navigationViewStyle(StackNavigationViewStyle())
}
else{
ZStack{
NavigationLink(destination: SignUp(show: self.$show), isActive: self.$show) {
Text("")
}
.hidden()
Login(show: self.$show)
}
}
}
.navigationBarTitle("")
.navigationBarHidden(true)
.navigationBarBackButtonHidden(true)
.onAppear {
NotificationCenter.default.addObserver(forName: NSNotification.Name("status"), object: nil, queue: .main) { (_) in
self.status = UserDefaults.standard.value(forKey: "status") as? Bool ?? false
}
}
}
}
For those that experience this, You can throw Text("").frame(width: UIScreen.main.bounds.width) at the bottom of ScrollView

Answer 1

Change your ObservableObject to:
class DiscoverPosts: ObservableObject { // make Types capitalised
#Published var posts: [Post] = [] // <- replace #State with #Published
init() {
getPosts()
}
func getPosts() { // <- no need for completion handler, update `self.posts`
let feedURL = "URL"
guard let url = URL(string: feedURL) else { return }
URLSession.shared.dataTask(with: url) { data, _, _ in
let posts = try! JSONDecoder().decode([Post].self, from: data!)
DispatchQueue.main.async {
self.posts = posts
}
}
.resume()
}
}
and use it in your view like this:
struct DiscoverView: View {
#ObservedObject var discoverPosts: DiscoverPosts // declare only
var body: some View {
ZStack {
...
}
//.onAppear { // <- remove onAppear
// self.discoverPosts.getPosts()
//}
}
}
You also need to pass DiscoverPosts to DiscoverView from Home view:
DiscoverView(discoverPosts: DiscoverPosts())
Note that if you previously accessed self.posts in your view, you will now need to access self.discoverPosts.posts