How download image from URL async

Question

I want to download image from url async but im unable to download im getting error Cannot invoke URLWithstring with an argument list of type'(url:$T3,(UIImage,NSError))->void . I am newer in iOS. Please help

user=array.objectAtIndex(indexPath.row).objectForKey("thumbnail_standard") as NSString
        downloadImage(url: NSURL.URLWithString(user)) { (var image:UIImage, var error:NSError) -> Void in
            println(image)
        }

func downloadImage(url: NSURL, handler: ((image: UIImage, error: NSError!) -> Void)) {
        var imageRequest: NSURLRequest = NSURLRequest(URL: url)
        NSURLConnection.sendAsynchronousRequest(imageRequest,
            queue: NSOperationQueue.mainQueue(),
            completionHandler:{response, data, error in
                handler(image: UIImage(data: data), error: error)
        })
    }

Answer 1

In my opinion, your error message says that the function that is supposed to be invoked is not same as how you defined.

why don't you try

downloadImage(url: NSURL.URLWithString(user)) { (var image:UIImage, var error:NSError!) -> Void in // exclamation added
    println(image)
}

rather than

downloadImage(url: NSURL.URLWithString(user)) { (var image:UIImage, var error:NSError) -> Void in
    println(image)
}

Hope this helps.