类型不符合 Alamofire 的协议“URLRequestConvertible”

Question

代码如下：

enum Router: URLRequestConvertible {
    //Error: Type 'Five100px.Router' does not conform to protocol 'URLRequestConvertible'

    static let baseURLString = "https://api.500px.com/v1"
    static let consumerKey = "MY_KEY"

    case PopularPhotos(Int)
    case PhotoInfo(Int, ImageSize)
    case Comments(Int, Int)

    var URLRequest: NSURLRequest {

        let (path, parameters) : (String, [String: AnyObject]) = {

            switch self {

            case .PopularPhotos(let page):
                let params = ["consumer_key": Router.consumerKey, "page": "\(page)", "feature": "popular", "rpp": "50", "include_store": "store_download", "include_status": "votes"]
                return ("/phtos", params)

            case .PhotoInfo(let photoID, let ImageSize):
                var params = ["consumer_key": Router.consumerKey, "image_size": "\(ImageSize.rawValue)"]
                return ("/photos/\(photoID)", params)

            case .Comments(let photoID, let commentsPage):
                var params = ["consumer_key": Router.consumerKey, "comments": "1", "comments_page": "\(commentsPage)"]
                return ("/photos/\(photoID)/comments", params)
            }
        }()

        let URL = NSURL(string: Router.baseURLString)
        let URLRequest = NSURLRequest(URL: URL!.URLByAppendingPathComponent(path))
        let encoding = Alamofire.ParameterEncoding.URL

        return encoding.encode(URLRequest, parameters: parameters).0
    }
}

我导入了 Alamofire 并添加了此代码，然后出现错误。我根据 raywenderlich 教程编写了这段代码：http://www.raywenderlich.com/85080/beginning-alamofire-tutorial，它是在我使用 Swift 2 时用 Swift 1.2 编写的。

Answer 1

您需要在URLRequest 属性中返回NSMutableURLRequest 而不是NSURLRequest。这将修复错误。

---

更新

在 Swift 3 和 Alamofire 4 中，您需要从新的 asURLRequest() 方法返回一个 URLRequest。有关详细信息，请参阅我们更详细的 README examples。

Answer 2

@cnoon 的回答适用于版本 3，但如果您使用的是 Alamofire 版本 4+，则必须实施：

func asURLRequest() throws -> URLRequest