Swift 4中的通用解码器 [英] Generic Decoders in Swift 4

问题描述

当前，我正在使用此代码来处理一些数据的解码：

Currently I'm using this code to handle decoding some data:

private func parseJSON(_ data: Data) throws -> [ParsedType] 
{
    let decoder = JSONDecoder()
    let parsed = try decoder.decode([ParsedType].self, from: data)
    return parsed
}

private func parsePlist(_ data: Data) throws -> [ParsedType] 
{
    let decoder = PropertyListDecoder()
    let parsed = try decoder.decode([ParsedType].self, from: data)
    return parsed
}

是否有一种方法可以创建将所有重复代码联系在一起的通用方法？

Is there a way to create a generic method that ties all this repeated code together?

private func parse(_ data: Data, using decoder: /*Something*/) throws -> [ParsedType]
{
    let parsed = try decoder.decode([ParsedType].self, from: data)
    return parsed
}

推荐答案

如果您查看 JSONEncoder 和 PropertyListDecoder 您会看到它们都共享一个方法

If you look at the swift stdlib for JSONEncoder and PropertyListDecoder you will see that they both share a method

func decode<T: Decodable >(_ type: T.Type, from data: Data) throws -> T

因此，您可以创建一个具有上述方法的协议，并使两个解码器都符合该方法：

So you could create a protocol that has said method and conform both decoders to it:

protocol DecoderType {
    func decode<T: Decodable >(_ type: T.Type, from data: Data) throws -> T
}

extension JSONDecoder: DecoderType { }
extension PropertyListDecoder: DecoderType { }

并创建通用解析函数，如下所示：

And create your generic parse function like so:

func parseData(_ data: Data, with decoder: DecoderType) throws ->  [ParsedType] {
    return try decoder.decode([ParsedType].self, from: data)
}

这篇关于Swift 4中的通用解码器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！