Swift2 - CallBack 예제

비동기식 데이터에서 콜백함수를 넣어야함.

func loadImage(urlString:String, handler:(image:UIImage?)-> Void)
{

  var imgURL: NSURL = NSURL(string: urlString)!
  let request: NSURLRequest = NSURLRequest(URL: imgURL)
  NSURLConnection.sendAsynchronousRequest(
    request, queue: NSOperationQueue.mainQueue(),
    completionHandler: {(response: NSURLResponse!,data: NSData!,error: NSError!) -> Void in
      if error == nil {
        handler(image: UIImage(data: data))
      }else{
        handler(image: nil)
      }
  })
}

Call func like this:

loadImage("someurl", { (image) -> Void in
  if let image = image{
   view.image.image = image
  }
})