ios - “(_, _, _) -> Void”无法转换为 'Result -> Void'

Question

在 View Controller 中我有以下代码:

newPost!.save({ (post, error) in
        //Error here. 

        if let anError = error {
            print("error calling POST on /posts")
            print(anError)
            return
        }
        guard let post = post else {
            print("error calling POST on /posts: result is nil")
            return
        }
        // success!
        print(post.description())
        print(post.title)

    })

我不太明白Result<Whatever>语法，Result应该是来自 Alamofire 2, Post是我创建的一个类，但是 Result<Post> -> Void 是做什么用的？完全意味着我应该改变什么？

更新:

func save(completionHandler: (Result<Post>) -> Void) {

let fields: [String: AnyObject]? = self.toJSON()
if fields == nil {

print("Error: error converting newPost fields to JSON")
return

}

Answer 1

您的完成处理程序定义和调用它的方式不同，如果您想这样调用它，请为您的完成处理程序尝试类似的方法:

func save(completionHandler: (post:Post?, error:String?) -> Void) {

    let fields: [String: AnyObject]? = self.toJSON()
    if fields == nil {
       completionHandler(nil, "Error converting newPost fields to JSON")
       return
    }
    // rest of code, eventually call completionHandler with success
}

对于 Swift 2:

func save(completionHandler: (post:Post?, error:String?) -> Void) {

    guard let fields = self.toJSON() else {
         completionHandler(nil, "Error converting newPost fields to JSON")
         return
    }
    // rest of code, eventually call completionHandler with success

}

Closures Documentation