Exporting JSON data to file via SwiftUI Modal Presentation.swift

import SwiftUI
import UniformTypeIdentifiers

struct MyStruct: Codable, Identifiable {
	let id: Int
	var name: String
}

struct ContentView: View {
	@State private var structs = [MyStruct]()
	@State private var isExporting = false
	@State private var isImporting = false

	var body: some View {
		VStack {
			Button("Generate Dummy Data") {
				generateDummyData()
			}

			Button("Export") {
				isExporting = true
			}
			.fileExporter(isPresented: $isExporting, document: StructsDocument(structs: structs), contentType: .json) { result in
				switch result {
				case .success(let url):
					print("Exported to \(url)")
				case .failure(let error):
					print("Failed to export: \(error)")
				}
			}

			Button("Import") {
				isImporting = true
			}
			.fileImporter(isPresented: $isImporting, allowedContentTypes: [.json], allowsMultipleSelection: false) { result in
				switch result {
				case .success(let urls):
					guard let url = urls.first else { return }
					do {
						guard url.startAccessingSecurityScopedResource() else {
							print("Failed to gain secure access to the file")
							return
						}

						defer { url.stopAccessingSecurityScopedResource() }

						let data = try Data(contentsOf: url)
						var importedStructs = try JSONDecoder().decode([MyStruct].self, from: data)
						importedStructs = importedStructs.map { MyStruct(id: $0.id, name: $0.name.uppercased()) }
						structs = importedStructs
					} catch {
						print("Failed to read or decode file: \(error)")
					}
				case .failure(let error):
					print("Failed to import: \(error)")
				}
			}

			List(structs) { myStruct in
				Text("\(myStruct.id): \(myStruct.name)")
			}
		}
	}

	func generateDummyData() {
		structs = [
			MyStruct(id: 1, name: "Alice"),
			MyStruct(id: 2, name: "Bob"),
			MyStruct(id: 3, name: "Charlie")
		]
	}
}

struct StructsDocument: FileDocument {
	static var readableContentTypes: [UTType] { [.json] }
	static var writableContentTypes: [UTType] { [.json] }

	var structs: [MyStruct]

	init(structs: [MyStruct]) {
		self.structs = structs
	}

	init(configuration: ReadConfiguration) throws {
		guard let data = configuration.file.regularFileContents else {
			throw CocoaError(.fileReadCorruptFile)
		}
		structs = try JSONDecoder().decode([MyStruct].self, from: data)
	}

	func fileWrapper(configuration: WriteConfiguration) throws -> FileWrapper {
		let data = try JSONEncoder().encode(structs)
		return FileWrapper(regularFileWithContents: data)
	}
}

Thanks for sharing this–was able to take some bits and peaces from this in my own app and have it working in no time.