Simple Swift JSON File Load

README.md

Simple Swift JSON loading example with typing

execute example

run main.swift file

# Swift version 5.0.1 (swift-5.0.1-RELEASE)

$ swiftc -o main JSONLoad.swift main.swift
$ ./main

# expected output: ExampleData(name: "test")

example.json

{
  "name": "test"
}

JSONLoad.swift

import Foundation

func load<T:Decodable>(_ filename:String, as type:T.Type = T.self) -> T {
  let data:Data
  guard let file = Bundle.main.url(forResource: filename, withExtension: nil)
  else {
    fatalError("Couldn't find \(filename) in main bundle.")
  }
  
  do {
    data = try Data(contentsOf: file)
  } catch {
    fatalError("Couldn't \(filename) from main bundle:\n\(error)")
  }
  
  do {
    let decoder = JSONDecoder()
    return try decoder.decode(T.self, from: data)
  } catch {
    fatalError("Couldn't parse \(filename)as \(T.self):\n\(error)")
  }
}

main.swift

struct ExampleData: Hashable, Codable {
  var name:String
}

let x:ExampleData = load("example.json")

print(x)

// expected output: ExampleData(name: "test")