Load JSON

load

👉 SwiftUI Tutorials ⟩ Building Lists & Navigation ⟩ Create a Landmark Model - Step 9

另外的方法請看： 將 Data 轉為 Swift 型別

import Foundation
import Combine                      // for `ObservableObject`

final class ModelData: ObservableObject {
    // ⭐️ load initial data from JSON
    @Published var landmarks: [Landmark] = load("landmarkData.json")
}

/// ⭐️ fetches JSON data from app’s main bundle.
/// - Returns: an instance of a type conforming to `Decodable`
func load<T: Decodable>(_ filename: String) -> T {
    
    // prepare to get data from file
    let data: Data

    // get file URL from app's main bundle
    // 1. filename -> URL
    guard
        let file = Bundle.main.url(forResource: filename, withExtension: nil)
    else {
        fatalError("Couldn't find \(filename) in main bundle.")
    }

    // 2. URL -> Data
    do {
        data = try Data(contentsOf: file)
    } catch {
        fatalError("Couldn't load \(filename) from main bundle:\n\(error)")
    }

    // 3. Data -> T
    do {
        let decoder = JSONDecoder()
        return try decoder.decode(T.self, from: data)
    } catch {
        fatalError("Couldn't parse \(filename) as \(T.self):\n\(error)")
    }
}

📘 手冊

👥 相關

• 將 Data 轉為 Swift 型別 - URLSession.DataTaskPublisher