展开 ViewController 之前的验证

Question

Is there a way to do a validation before unwind a ViewController?

i have my ViewController1 and there is a unwind function

    @IBAction func unwind(segue: UIStoryboardSegue) {

       // make stuff with data
}

And a button from ViewController2 is conected with that unwind function, and i pass data from my ViewController2 to ViewController1 in override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) all works fine, but i want to do some validations.

if sender as? UIBarButtonItem == self.saveButton  {

        if let content = self.textFieldContent.text {
            publish.content = content
            publish.image = self.image
        } else { 
           self.alertMessage("Content is empty")
        }

    }

The self.alertMessage() function appears but the ViewController2 is dismissed every time. And i dont want this to happens, how can i achieve that?

Answer 1

如果您需要防止在某些情况下展开，请改用 - (BOOL)shouldPerformSegueWithIdentifier:(NSString *)identifier sender:(id)sender 方法。