ios - Swift 3.0 迁移后 Alamofire 错误 : "Cannot convert value of type ' (URL, HTTPURLResponse)-> (URL )' to expected argument type ' 参数'"？

Question

我目前正在将我的代码库更新到 Swift 3.0。我正在使用 Alamofire。我不得不将 Alamofire 更新到 4.0 ( Alamofire git repo )。我有一种下载媒体(视频)的方法，在迁移之前它工作得很好。使用 Xcode 的迁移工具后，我遇到了这个错误:“无法将类型 '(URL, HTTPURLResponse)-> (URL)' 的值转换为预期的参数类型 'Parameters?'，这是一个 [String: Any]。到底是什么是这个Parameters对象吗？为什么它会抛出错误？迁移之前的这段代码和现在的唯一区别是现在NSURL被URL替换了。任何帮助都会很棒，因为我在过去的3个小时里一直坚持这个。

let mediaSourceURI: String = media.sourceURI
var filePath: URL?
let destination: (URL, HTTPURLResponse) -> (URL) = {
    (temporaryURL, response) in

    if let directoryURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first, let suggestedFilename = response.suggestedFilename {
        filePath = directoryURL.appendingPathComponent("\(suggestedFilename)")
        return filePath!
    }
    return temporaryURL
}

//ERROR BELOW:  "destination" is highlighted, and says "Cannot convert value of type '(URL, HTTPURLResponse)-> (URL)' to expected argument type 'Parameters?"
RequestManager.mediaDownloadAlamofireManager.download(mediaSourceURI, method: .get, parameters: destination).response {
    (request, response, data, error) -> Void in

    self.completeOperation()

}

这是我一直试图用作引用的链接: Alamofire 4.0 Migration Guide ，特别是在参数编码协议(protocol)部分。

以下是 Alamofire 中更新的下载方法的语法:


//mediaDownloadAlamofireManager 代码，没有错误:

static let mediaDownloadAlamofireManager: SessionManager = {
    let configuration = URLSessionConfiguration.default
    configuration.httpAdditionalHeaders = SessionManager.defaultHTTPHeaders
    let serverTrustPolicies: [String: ServerTrustPolicy] = [baseURL : .disableEvaluation]
    let manager = SessionManager(
        configuration: configuration,
        serverTrustPolicyManager: ServerTrustPolicyManager(policies: serverTrustPolicies)
    )
    return manager
}()

Answer 1

1. 简单的错字

RequestManager.mediaDownloadAlamofireManager.download(mediaSourceURI,method: .get, parameters: destination)

和

RequestManager.mediaDownloadAlamofireManager.download(mediaSourceURI,method: .get, destination: destination)

2.DownloadFileDestination-Type 的变化
Alamofire 4.0 changed the type的 DownloadFileDestination – 您调用的参数 目的地 .它从:

(URL, HTTPURLResponse) -> (URL)

到

(URL, HTTPURLResponse) -> (URL, DownloadRequest.DownloadOptions)

因此，您还需要将方法更改为以下内容:

let destination: (URL, HTTPURLResponse) -> (URL, DownloadRequest.DownloadOptions) = {
    (temporaryURL, response) in
        
    if let directoryURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first, let suggestedFilename = response.suggestedFilename {
        filePath = directoryURL.appendingPathComponent("\(suggestedFilename)")
        return (filePath!, [.removePreviousFile, .createIntermediateDirectories])
    }
    return (temporaryURL, [.removePreviousFile, .createIntermediateDirectories])
}

请注意，您不再只是返回 url，而且还有 more control over how Alamofire stores files on the file system .只需指定您想要的选项，例如 removePreviousFile 或/和 createIntermediateDirectories。它们现在以 Tuple 的形式返回。 .