CODEWITHSUNDEEP
swift2xcode7
Mike U
Mike U

Reputation: 3061

Swift 2 NSURLSession.sharedSession().dataTaskWithURL Cannot invoke with an argument list of type

Cant seem to get the following code to compile with Xcode 7, I get error "Cannot invoke 'dataTaskWithURL' with an argument list of type"

Looks like completionHandler is no longer optional, cant figure out how to rewrite the following code. Any help appreciated, Thanks

    let session = NSURLSession.sharedSession()
    let url = NSURL(string: urlString)

    var task = session.dataTaskWithURL(url!) {
        (data, response, error) -> Void in

        if error != nil {
            print(error!.localizedDescription)
        }
        else {
            var error: NSError?

            var jsonData = try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableContainers) as! NSArray
            // Do Stuff
        }
    }

    task!.resume()

Upvotes: 1

Views: 11133

Answers (3)

priyanka gautam
priyanka gautam

Reputation: 377

let url : String = String(format: "http://api.nytimes.com/svc/news/v3/content/nyt/all/720.json?api-key=%@",apiKey)
        let url1: NSURL = NSURL(string: url)!
      let session = NSURLSession.sharedSession()
        let task1 = session.dataTaskWithURL(url1, completionHandler: {
            (data, response, error) -> Void in
                        do {
                         if data == nil {
                    return
                }
                else
                {

                let jsonData = try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableContainers) as! NSDictionary
                self.dict = jsonData;
                self.array1 = (self.dict.objectForKey("results") as? NSMutableArray)!
                dispatch_async(dispatch_get_main_queue()) {
                    self.table.reloadData()
                }

                }

            } catch {

            }

        })

Upvotes: 1

jrc
jrc

Reputation: 21881

As of Swift 2.0 (Xcode 7 beta 6), use dataTaskWithURL() like this:

var task = session.dataTaskWithURL(url!, completionHandler: {
   (data, response, error) -> Void in

   :
})
task.resume()

To use NSJSONSerialization.JSONObjectWithData within the completion handler, you will also need catch errors:

    do {
        var jsonData = try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableContainers) as! NSArray
        // Do Stuff
    } catch {
        // handle error
    }

Upvotes: 2

Tomas Camin
Tomas Camin

Reputation: 10086

The compiler is throwing the following error:

/Users/Xcode/Desktop/fdsfsdfds/fdsfsdfds/AppDelegate.swift:24:28: Cannot invoke 'dataTaskWithURL' with an argument list of type '(NSURL, (_, _, _) throws -> Void)'

In the completionHandler you're not catching the exceptions that JSONObjectWithData may eventually throw. Therefore the compiler infers that you're trying to propagate the exception which would require that the completionHandler had the following signature:

(NSData?, NSURLResponse?, NSError?) throws -> Void

This does not match with the actual completionHandler dataTaskWithURL is expecting and thus the error.

To solve this issue simply wrap your call to NSJSONSerialization.JSONObjectWithData is a do/catch statement as follows to handle the error:

do {
    var jsonData = try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableContainers) as! NSArray
    // Do Stuff

} catch {
    // handle error
}

For more informations about error handling in Swift2 refer to the prerelease documentation available here

Upvotes: 9

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