NSURLSessionDataTask: func receives but returns no data - xcode

Question

I've tried to create a simple function which receives URL and simply returns the HTML of the webpage. the NSURLSessionDataTask itself seems to work, I can see the whole html when I println(data). But the func only returns the initial value "#!?". I suspect that the DataTask works asynchronous? How can I handle this?
func loadHTML(targetURL: String) -> String {
var theTargetURL = NSURL(string:targetURL)
var theResult = "#!?"
var request: NSURLRequest = NSURLRequest(URL:theTargetURL)
let config = NSURLSessionConfiguration.defaultSessionConfiguration()
let session = NSURLSession(configuration: config)
let task : NSURLSessionDataTask = session.dataTaskWithRequest(request, completionHandler: {(data, response, error) in
println(NSString(data: data, encoding: NSASCIIStringEncoding))
if error != nil {
println(error.localizedDescription)
theResult = "error"
}
if data != nil {
theResult = NSString(data: data, encoding: NSASCIIStringEncoding)
println("RECEIVED\t\t\(countElements(theResult)) CHARS")
}
});
task.resume()
return theResult
}

Answer 1

Here is an example how you would do it using a completion handler.
typealias CompletionBlock = (NSData!, NSURLResponse!, NSError!) -> Void
func loadHtml(targetUrlString: String, completion: CompletionBlock){
let targetUrl = NSURL(string: targetUrlString)
let request = NSURLRequest(URL: targetUrl)
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithRequest(request, completionHandler: completion)
task.resume()
}
Then, call it from your method where it is needed,
func viewDidLoad(){
super.viewDidLoad()
loadHtml("http://google.com", completion: { (responseData: NSData!, response: NSURLResponse!, error: NSError!) -> Void in
if responseData != nil{
let resultString = NSString(data: responseData, encoding: NSASCIIStringEncoding)
println(resultString)
/*
do some task or update on the main thread
dispatch_async(dispatch_get_main_queue){
myActivityIndicator.stopAnimating()
}
*/
}else if error != nil{
println("Error occurred: \(error.localizedDescription)")
}
})