I am currently following the tutorial from Hacking with swift url: (https://www.hackingwithswift.com/books/ios-swiftui/introduction-to-swiftdata-and-swiftui) to integrate SwiftData into a SwiftUI project. The code generated based on the tutorial is provided below. However, an error occurs upon launching the app: SwiftData/ModelContainer.swift:144: Fatal error: failed to find a currently active container for Student
.
I am seeking assistance in resolving this issue.
import SwiftUI
import SwiftData
@Model
class Student {
var id: UUID
var name: String
init(id: UUID, name: String) {
self.id = id
self.name = name
}
}
@main
struct project8App: App {
var body: some Scene {
WindowGroup {
VStack {
ContentView()
}
}
.modelContainer(for: Student.self)
}
}
struct ContentView: View {
@Environment(\.modelContext) var modelContext
@Query var students: [Student]
let allStudents = [
Student(id: UUID(), name: "John"),
Student(id: UUID(), name: "Paul"),
Student(id: UUID(), name: "George"),
Student(id: UUID(), name: "Ringo"),
]
var body: some View {
VStack {
ForEach(students) { student in
Text("\(student.name)")
}
Button(action: {
// random student
let student = allStudents.randomElement()!
modelContext.insert(student)
}) {
Text("Add/Change name")
}
}
}
}
P.S. It appears that the problem may be related to the container not being initialized by .modelContainer(for: Student.self)
. I have managed to resolve the error with the modified version below. However, I am still curious about the reasons behind the original version's malfunction and the differences between the two implementations.
// version 2, which is ok to run
@main
struct project8App: App {
let modelContainer: ModelContainer
init() {
do {
modelContainer = try ModelContainer(for: Student.self)
} catch {
fatalError("Could not initialize ModelContainer")
}
}
var body: some Scene {
WindowGroup {
VStack {
ContentView()
}
}
.modelContainer(modelContainer)
}
}