如何使用SwiftUI阻止DB在SQLite中多次创建？

import SwiftUI
import SQLite

class DatabaseManager {
    static let shared = DatabaseManager()
    private let db: Connection?

    private init() {
        let path = NSSearchPathForDirectoriesInDomains(
            .documentDirectory, .userDomainMask, true
        ).first!
        let dbPath = "\(path)/myDatabase.sqlite"

        if !FileManager.default.fileExists(atPath: dbPath) {
            FileManager.default.createFile(atPath: dbPath, contents: nil, attributes: nil)
        }

        do {
            db = try Connection(dbPath)
            // Perform necessary operations on the database
            // For example, create tables and insert data
        } catch {
            db = nil
            print("Unable to open database. Error: \(error)")
        }
    }
}

struct ContentView: View {
    var body: some View {
        Text("Hello, World!")
            .onAppear {
                let _ = DatabaseManager.shared // Create the database instance
            }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}