swiftui Array contents updated inside function closure but does not persist in other views - ios

Question

When fetching data from my database, I update an array from the json received inside the fetching function. While inside the function, the array stays updated, but when I try to access the array in a separate view, the array is empty.
the code that fetches the data and updates the "events" array looks like this:
import Foundation
import SwiftUI
let apiUrl = "http://localhost:5000/"
class DataFetcher: ObservableObject {
#Published var events: [eventdata] = []
func fetchEvents(){
events.removeAll()
let url = NSMutableURLRequest(url: NSURL(string: apiUrl)! as URL)
url.httpMethod = "GET"
URLSession.shared.dataTask(with: url as URLRequest) { data, response, err in
if let err = err {
print(err.localizedDescription)
return
}
guard let response = response as? HTTPURLResponse else { return }
if response.statusCode == 200 {
guard let data = data else { return }
DispatchQueue.main.async {
do{
self.events = try JSONDecoder().decode([eventdata].self, from: data)
// print(self.events.last?.address)
}catch let err {
print("Error: \(err)")
}
}
} else {
print("HTTPURLResponse code: \(response.statusCode)")
}
}.resume()
//print(self.events.last?.address)
}
}
The view that calls this function looks like this:
import Foundation
import SwiftUI
struct CreateEventButton: View {
#ObservedObject var request = DataFetcher()
#State private var isPresentedEvent = false
#State private var eventName: String = ""
#State private var eventDescription: String = ""
#State private var selectedStartTime = Date()
#State private var selectedEndTime = Date()
#State private var startTimeStamp: String = ""
#State private var endTimeStamp: String = ""
#Binding var annotationSelected: Bool
var dateFormatter: DateFormatter {
let formatter = DateFormatter()
formatter.dateStyle = .full
return formatter
}
func send(_ sender: Any) {
let request = NSMutableURLRequest(url: NSURL(string: "http://localhost:5000/")! as URL)
request.httpMethod = "POST"
self.startTimeStamp = "\(self.selectedStartTime)"
self.endTimeStamp = "\(self.selectedEndTime)"
self.startTimeStamp.removeLast(5)
self.endTimeStamp.removeLast(5)
let postString = "b=\(self.eventName)&c=\(self.eventDescription)&d=\(self.startTimeStamp)&e=\(self.endTimeStamp)"
request.httpBody = postString.data(using: String.Encoding.utf8)
let task = URLSession.shared.dataTask(with: request as URLRequest) {
data, response, error in
if error != nil {
print("error=\(String(describing: error))")
return
}
print("response = \(String(describing: response))")
let responseString = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
print("responseString = \(String(describing: responseString))")
}
task.resume()
self.eventName = ""
self.eventDescription = ""
self.selectedStartTime = Date()
self.selectedEndTime = Date()
}
var body: some View {
//UNCOMMENT THIS STUFF BELOW TO MAKE AN EVENT CREATION BUTTON IN THE SHEET INSTEAD OF JUST DIRECTING TO A SHEET WITH THE EVENT CREATION DETAILS
Button(action: {
self.isPresentedEvent.toggle() //trigger modal presentation
}, label: {
Text("Create Event").font(.system(size: 18)).foregroundColor(Color(.darkGray)).shadow(radius: 8)
}).padding(EdgeInsets(top: 8, leading: 6, bottom: 8, trailing: 6))
.foregroundColor(.secondary)
.background(Color(.secondarySystemBackground))
.cornerRadius(50.0)
.sheet(isPresented: $isPresentedEvent, content:{
VStack{
TextField("Event Name", text: self.$eventName).padding()
TextField("Event Description", text: self.$eventDescription).padding()
Form {
DatePicker("When your event starts: ", selection: self.$selectedStartTime, in: Date()...)
}
Form {
DatePicker("When your event ends: ", selection: self.$selectedEndTime, in: Date()...)
}
HStack{
Button(action: {
self.isPresentedEvent.toggle()
self.annotationSelected = false
print("Start: \(self.selectedStartTime)")
print("End: \(self.selectedEndTime)")
self.send((Any).self)
}, label: {
Text("Create Event")
})
Button(action: {
self.isPresentedEvent.toggle()
self.request.fetchEvents()
print("yo yo \(self.request.events.last?.address)")
}, label: {
Text("Cancel")
})
}
Text("Create Event Button (Non Functional)").padding()
}
} )
}
}
Any insight on where I might be going wrong is much appreciated

Answer 1

Button(action: {
self.isPresentedEvent.toggle()
self.request.fetchEvents()
}, label: {
if self.request.events.count > 0 {
Text("hey we have requests!")
} else {
Text("Cancel")
}
})
woops posted the accidently before finishing. one sec.
I believe it's a timing issue. The view is rendered before your request finishes fetching your data. You can add an if statement like above to update your view once the data is fully fetched.