Swift 3 - Hide Elements

问题

Im trying to hide a element using swift 3. The element won't hide if its in session.dataTask, but if I move it outside session.dataTask the element hides fine. Is it possible to hide a element in session.dataTask?

@IBOutlet weak var login_box: UIStackView!



let task = session.dataTask(with: request as URLRequest) {
            (
            data, response, error) in

            guard let data = data, let _:URLResponse = response, error == nil else {
                print("error")
                return
            }

            //Following won't hide element
            self.login_box.isHidden = true
    }

//If placed here element hides fine
login_box.isHidden = true

task.resume()

回答1:

First of all you need to start URLSessionDataTask instance using resume and always perform UI changes on main thread.

let task = session.dataTask(with: request as URLRequest) { (data, response, error) in
     guard let data = data, let _:URLResponse = response, error == nil else {
          print("error")
          return
     }

     DispatchQueue.main.async {              
          self.login_box.isHidden = true
     }
}
task.resume()

It will take some time get response from server (depends on your internet speed), but if error is not nil then it will not hide your login_box because it is return from the block.

来源：https://stackoverflow.com/questions/41478673/swift-3-hide-elements