I have a `NSMutableArray`. Here is how I save it with `NSUserDefaults`:

```
var defaults = NSUserDefaults.standardUserDefaults()
defaults.setObject(downloadedFile as NSMutableArray, forKey: "myKey")

```

And here how I retrieve it:

```
var downloadedFilesFromUserDefaults:NSMutableArray = defaults.objectForKey("myKey") as NSMutableArray

```