title: How to append a new line to text file in Swift
body: <p>I'm working on application where I need to append a new line when i touch the button on iPhone.
  I did this all but every time it writes over what i have written.</p>
  
  <p>How to append a new line each time I press the button save.</p>
  
  <pre><code>import UIKit
  
  class ViewController: UIViewController {
  
  @IBOutlet weak var myAge: UITextField!
  override func viewDidLoad() {
      super.viewDidLoad()
      // Do any additional setup after loading the view, typically from a nib.
      // get the documents folder url
  }
  
  override func didReceiveMemoryWarning() {
      super.didReceiveMemoryWarning()
      // Dispose of any resources that can be recreated.
  }
  
  @IBAction func writeNow(sender: UIButton) {
      let documentDirectoryURL = try! NSFileManager.defaultManager().URLForDirectory(.DocumentDirectory, inDomain: .UserDomainMask, appropriateForURL: nil, create: true)
  
      let fileDestinationUrl = documentDirectoryURL.URLByAppendingPathComponent("fileForIphoneAbdulla.txt")
  
      var text = myAge.text
  
      do {
          try text!.writeToURL(fileDestinationUrl, atomically: true, encoding: NSUTF8StringEncoding)
          print("file is saved succefully")
  
          do {
              let mytext = try String(contentsOfURL: fileDestinationUrl, encoding: NSUTF8StringEncoding)
              print(mytext)   // "some text\n"
          } catch let error as NSError {
              print("error loading from url \(fileDestinationUrl)")
              print(error.localizedDescription)
          }
      } catch let error as NSError {
          print("error writing to url \(fileDestinationUrl)")
          print(error.localizedDescription)
      }
  }
  }
  </code></pre>