Useful for decoding JSON data from a file by passing in a type.

DataDecoder.swift

/* 
 * SPDX-FileCopyrightText: © 2023 Daniel Zhang <https://github.com/d108/>
 * SPDX-License-Identifier: MIT License
 */

import Foundation

struct DataDecoder
{
    /// Generic decoder with a switch statement to handle specific types.
    ///
    /// Usage example: 
    ///
    ///     let myData: MyData? = try DataDecoder.decode(dataType: MyData.self)
    ///
    /// - Parameter dataType: The type of data to decode.
    /// - Returns: The decoded data.
    static func decode<T: Codable>(dataType: T.Type) throws -> T?
    {
        var decodeWith: Codable.Type
        let decoder = JSONDecoder()
        var fileURL: URL?
        switch dataType
        {
        // Each case is a Codable type.
        case // Add any needed cases.
        default:
            return nil
        }
        if let url = fileURL, let data = try? Data(contentsOf: url)
        {
            return try? decoder.decode(decodeWith, from: data) as? T
        }
        throw DataError.decodeFailure
    }
}