无法将类型'(Any)->()'的值转换为预期的参数类型'(_)-> _'

时间:2018-09-08 13:22:44

标签: swift4 promisekit

安装PromiseKit(6.2.1)。 Swift4.0。

import UIKit
import PromiseKit

class ViewController: UIViewController {
    func onFulfilled() -> (String) -> Promise<String> {
        return { result in
            return Promise<String> { seal in
                print(result)
                DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(1), execute: {
                    seal.fulfill("Hello")
                })
            }
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        Promise.value("first")
            .then(onFulfilled())
            .then(onFulfilled())
            .then(onFulfilled())
            .then { result in print(result) } // Cannot convert value of type '(Any) -> ()' to expected argument type '(_) -> _'
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

错误

  

无法将类型'(Any)->()'的值转换为预期的参数类型'(_)-> _'

如何修复

如何修复.then { result in print(result) }

1 个答案:

答案 0 :(得分:0)

then替换为done

_ = Promise.value("first")
            .then(onFulfilled())
            .then(onFulfilled())
            .then(onFulfilled())
            .done { result in print(result) }

请参阅:https://github.com/mxcl/PromiseKit/blob/master/Documentation/GettingStarted.md

  

完成与那时相同,但是您不能返回承诺。它通常是链的“成功”部分的末端。