FileManager jsonFromFile only support json dictionary

[tospery]

FileManager.jsonFromFile extension do not support JSON array
e.g.

[ 
  {
   ... 
  }
]

[LucianoPAlmeida]

Thanks for reporting @tospery

[cHaLkdusT]

The problem is because of downcasting of the returned value.

SwifterSwift/Sources/SwifterSwift/Foundation/FileManagerExtensions.swift

Line 54 in fef7f4b

return json as? [String: Any]

Do we want to create another API that returns [[String: Any]] or refactor the existing API to return Any?, and let the caller to handle if they wanted to cast it to Dictionary or Array of Dictionaries instead?

[guykogus]

If we change the current API to return Any?, which would involve no casting, it'd be a breaking change, unfortunately. The current return type is completely wrong anyway, considering that the default parameter for readingOptions is .allowFragments, which would actually return nil if it was one.

I think the current functions should be deprecated and replaced with a new function returning Any?.

Alongside it I wouldn't mind having the same function for reading/writing. I actually have the following FileManager extensions in my projects (could use a little touch up, probably):

extension FileManager {
    enum FileError: LocalizedError {
        case failedToSave(path: String)
        case failedToLoad(path: String)

        var errorDescription: String? {
            switch self {
            case .failedToSave(let path):
                return "Failed to save file to path \(path)"
            case .failedToLoad(let path):
                return "Failed to save file to path \(path)"
            }
        }
    }

    func saveToJSON<T: Encodable>(_ object: T?,
                                  at url: URL,
                                  attributes: [FileAttributeKey: Any]? = nil) throws {
        guard let object = object else {
            if fileExists(atPath: url.path) {
                try removeItem(at: url)
            }
            return
        }

        let documentURL = url.deletingLastPathComponent()
        if !fileExists(atPath: documentURL.path) {
            try createDirectory(at: documentURL, withIntermediateDirectories: true, attributes: attributes)
        }

        let encoder = JSONEncoder()
        let data = try encoder.encode(object)
        let path = url.path
        guard createFile(atPath: path,
                         contents: data,
                         attributes: attributes) else {
                            throw FileError.failedToSave(path: path)
        }
    }

    func loadFromJSON<T: Decodable>(at url: URL) throws -> T? {
        guard fileExists(atPath: url.path) else { return nil }

        let decoder = JSONDecoder()
        let path = url.path
        guard let data = contents(atPath: path) else {
            throw FileError.failedToLoad(path: path)
        }
        return try decoder.decode(T.self, from: data)
    }
}