Why Swift 5 read local json always nil? - ios

Question

I've read lots of SO question on it, but they are not applying in my case.
I follow the steps mentioned in Parse JSON from file and URL with Swift, project structure is:
The code:
import Foundation
struct DemoData: Codable {
let title: String
let description: String
}
func readLocalFile(forName name: String) -> Data? {
do {
if let bundlePath = Bundle.main.path(forResource: name,
ofType: "json"),
let jsonData = try String(contentsOfFile: bundlePath).data(using: .utf8) {
return jsonData
}
} catch {
print(error)
}
return nil
}
func parse(jsonData: Data) {
do {
let decodedData = try JSONDecoder().decode(DemoData.self,
from: jsonData)
print("Title: ", decodedData.title)
print("Description: ", decodedData.description)
print("===================================")
} catch {
print("decode error")
}
}
if let localData = readLocalFile(forName: "data") {
print("running")
parse(jsonData: localData)
} else {
print("final nil")
}
And it turn out to be:
final nil
Program ended with exit code: 0
PS: Config of the json data

Answer 1

You are suppressing some potential errors, I recommend this (generic) version, it throws all possible errors
enum ReadError : Error { case fileIsMissing }
func readLocalFile<T : Decodable>(forName name: String) throws -> T {
guard let url = Bundle.main.url(forResource: name,
withExtension: "json") else {
throw ReadError.fileIsMissing
}
let jsonData = try Data(contentsOf: url)
return try JSONDecoder().decode(T.self, from: jsonData)
}
do {
let localData : DemoData = try readLocalFile(forName: "data")
print("===================================")
print("running")
print("Title: ", localData.title)
print("Description: ", localData.description)
print("===================================")
} catch {
print("An error occured", error)
}
Edit:
Your code doesn't work because your target is a command line tool.
CLIs don't have a bundle therefore there is no Resources folder either.

Answer 2

The problem might be with the text encoding format of the json file. Please check and it should be Unicode (UTF-8) since you're using text encoding format as .utf8 in readLocalFile file method.