Initializer for conditional binding must have Optional type, not 'URLSessionDataTask'

Question

I am getting this error, and after researching I still have no idea how to solve it.

Maybe it is something about swift 3 because it appeared when I updated it.

The exact error is in: guard let task = URLSession.shared.dataTask(with: request, completionHandler: {(data:Data?, response:URLResponse?, error:NSError?) -> Void in

I would appreciate any help.

Thanks

class func faceForPerson (_ person:String, size:CGSize, completion:@escaping (_ image:UIImage?, _ imageFound:Bool?)->()) throws {
    let escapedString = person.addingPercentEncoding(withAllowedCharacters: CharacterSet.urlHostAllowed)

    let pixelsForAPIRequest = Int(max(size.width, size.height)) * 2

    let url = URL(string: "https://en.wikipedia.org/w/api.php?action=query&titles=\(escapedString!)&prop=pageimages&format=json&pithumbsize=\(pixelsForAPIRequest)")
    var request = URLRequest(url:url! as URL);

    request.httpMethod = "GET";
    guard let task = URLSession.shared.dataTask(with: request, completionHandler: {(data:Data?, response:URLResponse?, error:NSError?) -> Void in
        if error == nil {
            let wikiDict = try! JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.allowFragments) as! NSDictionary

            if let query = wikiDict.object(forKey: "query") as? NSDictionary {
                if let pages = query.object(forKey: "pages") as? NSDictionary {
                    if let pageContent = pages.allValues.first as? NSDictionary {
                        if let thumbnail = pageContent.object(forKey: "thumbnail") as? NSDictionary {
                            if let thumbURL = thumbnail.object(forKey: "source") as? String {
                                let faceImage = UIImage(data: try! Data(contentsOf: URL(string: thumbURL)!))

                                completion(faceImage, true)
                            }
                        }else{
                            completion(nil, false)
                        }
                    }
                }
            }


        }
    } as! (Data?, URLResponse?, Error?) -> Void)else{
        throw WikiFaceError.couldNotDownloadImage
    }

    task!.resume()

}

completionHandler: {(data:Data?, response:URLResponse?, error:NSError?) -> Void in should be completionHandler: { data, response, error in — Leo Dabus
var request = URLRequest(url:url! as URL); makes no sense. use just var request = URLRequest(url: url!) — Leo Dabus
You can put multiple bindings in a single if statement to avoid that pyramid of dom. — Alexander

Tj3n Tj3n · Accepted Answer · 2016-12-01T04:34:58

This guard let task = URLSession.shared.dataTask(with: request, completionHandler: {(data:Data?, response:URLResponse?, error:NSError?) -> Void in doesn't create optional data task (it wont be nil), so you don't need to check optional with guard let, just use let

Also makes no sense you tried to force it become (Data?, URLResponse?, Error?) -> Void)?

Initializer for conditional binding must have Optional type, not 'URLSessionDataTask'

1 Answers