I went back to swift programming after 4 years and everything changed. I learn everything from scratch. I'm trying to solve a variable binding problem. I want to build a dynamic form with fields that will come back from API. Code:
import SwiftUI
struct Filter: Codable, Identifiable {
var id: Int
var name: String
var type: String
var defaultValue: Int
init(_ dictionary: [String: Any]) {
self.id = dictionary["id"] as? Int ?? 0
self.name = dictionary["name"] as? String ?? ""
self.type = dictionary["type"] as? String ?? ""
self.defaultValue = dictionary["defaultValue"] as? Int ?? 0
}
}
struct ContentView: View {
@State var filters:Array<Filter> = []
func load(){
guard let url = URL(string: "https://api.kierklosebastian.pl/") else {return}
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
guard let dataResponse = data,
error == nil else {
print(error?.localizedDescription ?? "Response Error")
return }
do {
let decoder = JSONDecoder()
let model = try decoder.decode([Filter].self, from:
dataResponse)
self.filters = model;
} catch let parsingError {
print("Error", parsingError)
}
}
task.resume()
}
var body: some View {
VStack{
Button(action: self.load, label: {
Text("Get json")
})
List{
ForEach(self.filters) { filter in
HStack{
Text("NAME: \(filter.name)")
Text("TYPE: \(filter.type)")
if filter.type == "textField" {
// TextField("", ???????)
}
if filter.type == "checkbox" {
// Toggle(isOn: ????????) {
// ""
// }
}
}
}
}
}
}
}
How do I declare the TextFiled and Toggle variables?
Toggle needs to have a boolean binding property that determines whether the toggle is on or off. So you need to define a boolean property somehwere, for ex, for Filter.
struct Filter: Codable, Identifiable {
var id: Int
var name: String
var type: String
var defaultValue: Int
var isOn: Bool = false
init(_ dictionary: [String: Any]) {
self.id = dictionary["id"] as? Int ?? 0
self.name = dictionary["name"] as? String ?? ""
self.type = dictionary["type"] as? String ?? ""
self.defaultValue = dictionary["defaultValue"] as? Int ?? 0
self.isOn = (dictionary["type"] as? String ?? "") == "checkbox"
}
}
Create a view model that confirms to ObservableObject.
https://developer.apple.com/documentation/combine/observableobject
class FilterViewModel: ObservableObject {
@Published var filters:Array<Filter> = []
func load(){
guard let url = URL(string: "https://api.kierklosebastian.pl/") else {return}
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
guard let dataResponse = data,
error == nil else {
print(error?.localizedDescription ?? "Response Error")
return }
do {
let decoder = JSONDecoder()
let model = try decoder.decode([Filter].self, from:
dataResponse)
self.filters = model;
} catch let parsingError {
print("Error", parsingError)
}
}
task.resume()
}
}
And use it instead of @State var filters:Array<Filter> = [] in ContentView.
struct FilterView: View {
@ObservedObject var viewModel = FilterViewModel()
-----
}
Create a new view for the content of the ForEach and pass viewModel and filter to it. In the new view, find index of the current filter.
struct FilterDetailView: View {
@ObservedObject var viewModel: FilterViewModel
var filter: Filter
var indexOfFilter: Int {
self.viewModel.filters.firstIndex { $0 == filter}!
}
var body: some View {
HStack{
Text("NAME: \(filter.name)")
Text("TYPE: \(filter.type)")
if filter.type == "textField" {
TextField("TextField", text: self.$viewModel.filters[indexOfFilter].name)
}
if filter.type == "checkbox" {
Toggle(isOn: self.$viewModel.filters[indexOfFilter].isOn) {
Text("Toggle")
}
}
}
}
}
You need to confirm to Equatable too. Oterwise, you can not use firstIndex { $0 == filter}!
struct Filter: Codable, Identifiable, Equatable {
}
struct Filter: Codable, Identifiable, Equatable {
var id: Int
var name: String
var type: String
var defaultValue: Int
var isOn: Bool = false
init(_ dictionary: [String: Any]) {
self.id = dictionary["id"] as? Int ?? 0
self.name = dictionary["name"] as? String ?? ""
self.type = dictionary["type"] as? String ?? ""
self.defaultValue = dictionary["defaultValue"] as? Int ?? 0
self.isOn = (dictionary["type"] as? String ?? "") == "checkbox"
}
}
class FilterViewModel: ObservableObject {
@Published var filters:Array<Filter> = []
func load(){
guard let url = URL(string: "https://api.kierklosebastian.pl/") else {return}
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
guard let dataResponse = data,
error == nil else {
print(error?.localizedDescription ?? "Response Error")
return }
do {
let decoder = JSONDecoder()
let model = try decoder.decode([Filter].self, from:
dataResponse)
self.filters = model;
} catch let parsingError {
print("Error", parsingError)
}
}
task.resume()
}
}
struct FilterView: View {
@ObservedObject var viewModel = FilterViewModel()
var body: some View {
VStack{
Button(action: self.viewModel.load, label: {
Text("Get json")
})
List{
ForEach(self.viewModel.filters) { filter in
FilterDetailView(viewModel: viewModel, filter: filter)
}
}
}
}
}
struct FilterDetailView: View {
@ObservedObject var viewModel: FilterViewModel
var filter: Filter
var indexOfFilter: Int {
self.viewModel.filters.firstIndex { $0 == filter}!
}
var body: some View {
HStack{
Text("NAME: \(filter.name)")
Text("TYPE: \(filter.type)")
if filter.type == "textField" {
TextField("TextField", text: self.$viewModel.filters[indexOfFilter].name)
}
if filter.type == "checkbox" {
Toggle(isOn: self.$viewModel.filters[indexOfFilter].isOn) {
Text("Toggle")
}
}
}
}
}
ForEach(self.viewModel.filters) { $filter in
-----
}
Toggle(isOn: $filter.isOn) {
Text("Toggle")
}
If you are interested, watch What's new in SwiftUI - WWDC21 (08:00) and follow Apple's SwiftUI Tutorials