FileManager+Extension.swift

extension FileManager {
    static var documentsDirectory: URL {
        let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
        return paths[0]
    }
    
    enum ObjectStorageError: Error {
        case objectDoesNotExist
        case objectHasWrongType
        case couldNotEncodeObject
        
        var description: String {
            switch self {
            case .objectDoesNotExist: return "Object Does Not Exist"
            case .objectHasWrongType: return "Object Has Wrong Type"
            case .couldNotEncodeObject: return "Could Not Encode Object"
            }
        }
    }

    static func readJSONObject<Object: Decodable>(ofType type: Object.Type,
                                                  atUrl url: URL) throws -> Object {
        do {
            let data = try Data(contentsOf: url)
            return try JSONDecoder().decode(type, from: data)
        } catch {
            throw ObjectStorageError.objectDoesNotExist
        }
    }
    
    static func writeJSONObject<Object: Encodable>(_ object: Encodable,
                                              ofType type: Object.Type,
                                              atUrl url: URL) throws {
        guard let object = object as? Object else {
            throw ObjectStorageError.objectHasWrongType
        }
        do {
            let data = try JSONEncoder().encode(object)
            try data.write(to: url, options: [.atomicWrite, .completeFileProtection])
        } catch {
            throw ObjectStorageError.couldNotEncodeObject
        }
    }
    
    static func deleteObject(atUrl url: URL) throws {
        do {
            try FileManager.default.removeItem(at: url)
        } catch {
            throw error
        }
    }
}