dataTaskWithRequest之后的Dispatch_async

Question

在我的应用用户点按标记，我需要调用网络服务才能获取信息。我使用NSURLSession.dataTaskWithRequest然后在主队列上调用dispatch_async以向用户显示标记。但是我在dispatch_async

中尝试传递参数时遇到错误

代码如下

func mapView(mapView: GMSMapView!, markerInfoWindow marker: GMSMarker!) -> UIView! {

    let request = NSMutableURLRequest(URL: NSURL(string: "http://78.27.190.58:3300/api/get_location_ratings")!)
    request.HTTPMethod = "POST"
    let postString = "org_id=\(marker.userData["orgId"] as! Int)"
    request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)

    let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {

        data, response, error in

        var json = JSON(data: data!)

        var rating = json["results"]["avg_stars"].doubleValue

        dispatch_async(dispatch_get_main_queue()) { (mapView: GMSMapView!, markerInfoWindow marker: GMSMarker!) -> UIView! in

            self.window = NSBundle.mainBundle().loadNibNamed("infoWindow", owner: self, options: nil).first! as! infoWindow

            self.window?.name.text = marker.title
            self.window?.adress.text = marker.snippet
            self.window?.stars.image = UIImage(named: "\(showStars((marker.userData["Rating"] as! NSString).doubleValue))")
            self.window?.rating.text = String((marker.userData["Rating"] as! NSString).doubleValue)

            return window


        }

    }

    task.resume()
}

错误是

我做错了什么？

Answer 1

在您的dispatch_async中，您使用了包含两个参数（mapView和marker）的闭包，但没有将任何内容传递给这些参数。

Answer 2

因为您使用dataTaskWithRequest，所以您无法直接返回值。所以你必须在这种情况下使用闭包。您可以将代码更改为：

func mapView(mapView: GMSMapView!, markerInfoWindow marker: GMSMarker!, completion:(UIView!) -> Void)  {

    let request = NSMutableURLRequest(URL: NSURL(string: "http://78.27.190.58:3300/api/get_location_ratings")!)
    request.HTTPMethod = "POST"
    let postString = "org_id=\(marker.userData["orgId"] as! Int)"
    request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)

    let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {

        data, response, error in

        var json = JSON(data: data!)

        var rating = json["results"]["avg_stars"].doubleValue

        dispatch_async(dispatch_get_main_queue()) {

            let view = UIView(frame: self.view.frame)

            self.window = NSBundle.mainBundle().loadNibNamed("infoWindow", owner: self, options: nil).first! as! infoWindow

            self.window?.name.text = marker.title
            self.window?.adress.text = marker.snippet
            self.window?.stars.image = UIImage(named: "\(showStars((marker.userData["Rating"] as! NSString).doubleValue))")
            self.window?.rating.text = String((marker.userData["Rating"] as! NSString).doubleValue)

            completion(window)


        }

    }

    task.resume()
}

并使用它：

your_instace.mapView(mapview, markerInfoWindow: GMSMakre) { (view: UIView!) -> Void in
        //do somethinghere
    }