Question

我正试图在promise kit上链接一些承诺，当promise类型像Promise<Location>时，我有语法问题，只有当promise有一个类型我得到编译器错误时。我是使用promisekit的新手

Swift.start(host,"","").then{ result -> Void in

    }.then{ obj -> Void in
        println(obj)
        Swift.getCurrent.then{ obj -> Void in
            let payload:Dictionary<String,AnyObject> = obj as! Dictionary<String,AnyObject>
            self.deviceUUID = payload["uuid"] as! String

        }
    }.then { obj -> Location in
        println(obj)
        Swift.getLocation("3333").then{ location in
            self.locationUUID = location.get("uuid")
        }
    }

Answer 1

你的街区不需要退货：

.then { obj -> Location in
      Swift.getLocation("433434").then{ location in
          self.locationUUID = location.get("uuid")
      }
}

Answer 2

这里有很多问题。

你没有链接，因为你没有回复你的诺言。
你没有在第二个闭包中返回，这是编译错误，闭包说它返回Location但闭包返回Void

。

Swift.start(host, "", "").then { result -> Void in

}.then { obj -> Promise<Something> in
    print(obj)

    // I changed the return of this closure, see above
    // we must return the promise or we are not chaining
    return Swift.getCurrent.then { obj -> Void in
        let payload: Dictionary<String, AnyObject> = obj as! Dictionary<String, AnyObject>
        self.deviceUUID = payload["uuid"] as! String

    }
}.then { obj -> Location in
    println(obj)

    // we promised a return value above, so we must return
    return Swift.getLocation("3333").then { location in
        self.locationUUID = location.get("uuid")
    }
}

然而，看看你的代码，看起来似乎不正确，这实际上是你所追求的吗？

firstly { _ -> Promise<[String: AnyObject]> in
    return Swift.getCurrent
}.then { payload -> Promise<Location> in
    self.deviceUUID = payload["uuid"] as! String
    return Swift.getLocation("3333")
}.then { location -> Void in
    self.locationUUID = location.get("uuid")
}

PromiseKit语法链swift

2 个答案: