Display filename in next View too - swiftui

Question

I have a code that makes a http Request, gets an array with filenames from that, displays them each with an image and the filename below. Everything works fine.
Now I made each image a button that opens a detail page.
That works but at the top it should say the matching filename from the page before.
But I am not able to hand over the filename (name) from ContentView4 to the next page (ts).
The language is SwiftUi
Could you please help me?
Thanks
Nikias
Here is my code:
import SwiftUI
struct ContentView4: View {
#State var showingDetail = false
#State var username: String = "."
#State var password: String = "."
#State private var name = String("Nikias2")
#State private var t = String()
#State private var x = -1
#State var dateien = ["word.png"]
var body: some View {
ScrollView(.vertical) {
ZStack{
VStack {
ForEach(0 ..< dateien.count, id: \.self) {
Button(action: {
print("button pressed")
x = x + 1
t = dateien[x]
self.showingDetail.toggle()
}) {
Image("datei")
}
.scaledToFit()
.padding(0)
Text(self.dateien[$0])
Text(t)
.foregroundColor(.white)
}
}
}
.sheet(isPresented:
$showingDetail) {
ts(name: t)
}
.onAppear { //# This `onAppear` is added to `ZStack{...}`
doHttpRequest()
}
}
}
func doHttpRequest() {
let myUrl = URL(string: "http://192.168.1.180/int.php")! //# Trailing semicolon is not needed
var request = URLRequest(url: myUrl)
request.httpMethod = "POST"// Compose a query string
let postString = "Name=\($username)&Passwort=\($password)"
request.httpBody = postString.data(using: .utf8)
let task = URLSession.shared.dataTask(with: request) {
(data, response, error) in
//# Use if-let when you want to use the unwrapped value
if let error = error {
print("error=\(error)")
return
}
//# Use guard-let when nil has no meaning and want to exit on nil
guard let response = response else {
print("Unexpected nil response")
return
}
// You can print out response object
print("response = \(response)")
//Let's convert response sent from a server side script to a NSDictionary object:
do {
//# Use guard-let when nil has no meaning and want to exit on nil
guard let data = data else {
print("Unexpected nil data")
return
}
//#1 `mutableContainer` has no meaning in Swift
//#2 Use Swift Dictionary type instead of `NSDictionary`
let json = try JSONSerialization.jsonObject(with: data) as? [String: Any]
if let parseJSON = json {
// Now we can access value of First Name by its key
//# Use if-let when you want to use the unwrapped value
if let firstNameValue = parseJSON["Name"] as? String {
print("firstNameValue: \(firstNameValue)")
let dateien = firstNameValue.components(separatedBy: ",")
print(dateien)
self.dateien = dateien
}
}
} catch {
print(error)
}
}
task.resume()
}
}
struct TestView_Previews: PreviewProvider {
static var previews: some View {
ContentView4()
}
}
struct ts: View {
#State var hin = false
#State var um = false
#State var datname: String = ""
var name: String
var body: some View {
NavigationView {
VStack {
Text(name)
.font(.system(size: 60))
.foregroundColor(.black)
.padding(50)
Button(action: {
self.hin.toggle()
}) {
Text("+")
.font(.headline)
.foregroundColor(.white)
.padding()
.frame(width: 220, height: 60)
.background(Color.yellow)
.cornerRadius(35.0)
}
.padding()
if hin {
HStack {
Text("Datei auswählen")
.font(.headline)
.frame(width: 150, height: 70)
.background(Color.yellow)
.cornerRadius(20.0)
.animation(Animation.default)
Text("Datei hochladen")
.font(.headline)
.frame(width: 150, height: 70)
.background(Color.yellow)
.cornerRadius(20.0)
.animation(Animation.default)
}
}
Text("Datei herunterladen")
.font(.headline)
.foregroundColor(.white)
.padding()
.frame(width: 220, height: 60)
.background(Color.blue)
.cornerRadius(35.0)
Button(action: {
self.um.toggle()
}) {
Text("Datei umbenennen")
.font(.headline)
.foregroundColor(.white)
.padding()
.frame(width: 220, height: 60)
.background(Color.green)
.cornerRadius(35.0)
}
.padding()
if um {
HStack {
TextField(name, text: $datname)
.font(.headline)
.frame(width: 150, height: 70)
.cornerRadius(20.0)
.animation(Animation.default)
Text("Datei umbenennen")
.font(.headline)
.frame(width: 150, height: 70)
.background(Color.green)
.cornerRadius(20.0)
.animation(Animation.default)
}
}
Text("Datei löschen")
.font(.headline)
.foregroundColor(.white)
.padding()
.frame(width: 220, height: 60)
.background(Color.red)
.cornerRadius(35.0)
}
}
}
}

Answer 1

I believe your issue is a result of using #State variables to store all of the attributes. #State variables are not consistent and get refreshed in the background by SwiftUI depending on your views visibility.
The piece that you are missing is a view controller class stored in an #EnviornmentObject variable. This class gets Initiated in your main contentView and is used to keep track and alter of all your attributes.
Each ContentView should reference the single #EnviornmentObject and pull data from that class.
Another solution which may work would be to replace all your #State variables with #StateObject vars. #StateObject vars are basically #State vars but get initiated before the struct get loaded and the value is kept consistent regardless of the view state of the parent struct.
Here is a rough implementation of #EnvironmentObject within your project.
Basically use the #EnvironmentObject to pass values to child views
ContentView4.swift
struct ContentView4: View {
#EnvironmentObject cv4Controller: ContentView4Controller
var body: some View {
ScrollView(.vertical) {
ZStack{
VStack {
ForEach(0 ..< cv4Controller.dateien.count, id: \.self) {
Button(action: {
print("button pressed")
x = x + 1
t = cv4Controller.dateien[x]
self.showingDetail.toggle()
}) {
Image("datei")
}
.scaledToFit()
.padding(0)
Text(self.dateien[$0])
Text(cv4Controller.t)
.foregroundColor(.white)
}
}
}
.sheet(isPresented:
cv4Controller.$showingDetail) {
ts(name: cv4Controller.t)
}
.onAppear { //# This `onAppear` is added to `ZStack{...}`
cv4Controller.doHttpRequest()
}
}
}
ContentView4Controller.swift
class ContentView4Controller: ObservableObject {
#Published var showingDetail = false
#Published var username: String = "."
#Published var password: String = "."
#Published private var name = String("Nikias2")
#Published private var t = String()
#Published private var x = -1
#Published private var t = String()
#Published private var x = -1
#Published var dateien = ["word.png"]
func doHttpRequest() {
let myUrl = URL(string: "http://192.168.1.180/int.php")! //# Trailing semicolon is not needed
var request = URLRequest(url: myUrl)
request.httpMethod = "POST"// Compose a query string
let postString = "Name=\($username)&Passwort=\($password)"
request.httpBody = postString.data(using: .utf8)
let task = URLSession.shared.dataTask(with: request) {
(data, response, error) in
//# Use if-let when you want to use the unwrapped value
if let error = error {
print("error=\(error)")
return
}
//# Use guard-let when nil has no meaning and want to exit on nil
guard let response = response else {
print("Unexpected nil response")
return
}
// You can print out response object
print("response = \(response)")
//Let's convert response sent from a server side script to a NSDictionary object:
do {
//# Use guard-let when nil has no meaning and want to exit on nil
guard let data = data else {
print("Unexpected nil data")
return
}
//#1 `mutableContainer` has no meaning in Swift
//#2 Use Swift Dictionary type instead of `NSDictionary`
let json = try JSONSerialization.jsonObject(with: data) as? [String: Any]
if let parseJSON = json {
// Now we can access value of First Name by its key
//# Use if-let when you want to use the unwrapped value
if let firstNameValue = parseJSON["Name"] as? String {
print("firstNameValue: \(firstNameValue)")
let dateien = firstNameValue.components(separatedBy: ",")
print(dateien)
self.dateien = dateien
}
}
} catch {
print(error)
}
}
task.resume()
}
}
Example of main ContentView.swift
struct ContentView: View {
var cv4Controller: ContentView4Controller = ContentView4Controller()
var body: some view {
// your main page output
GeometryReader { geo in
// just a guess for what you have in your main contentView
switch(page) {
case .main:
ContentView2()
default:
ContentView4()
break
}
}.environmentObject(cv4Controller) // this will make cv4Controller available to all child view structs
}
}

Answer 2

Add #Binding wrapper to the "name" variable in your ts view. And pass the t variable as a binding by adding a "$". This will keep your ts name variable updated to whatever is value it has in the parent view.
Also why do you use a NavigationView in your ts View?
struct ContentView4: View {
...
#State private var t = String()
...
var body: some View {
...
ZStack{
...
}
.sheet(isPresented: $showingDetail) {
ts(name: $t)
}
...
}
func doHttpRequest() {
...
}
}
struct ts: View {
...
#Binding var name: String
var body: some View {
...
}
}

Answer 3

My starting code works, but It's just displaying the Filenames in a row and if I tap a random image, the name won't fit, only if I'm going down in the row and tap them. The problem is, that I don't know how to set the variable to the id, not to pass them to the next view. Has anyone got and idea how I can pass the right filename into a variable in the for loop and read it in the next view?