I am trying to unwrap a NSMutableArray from user defaults, but keep getting the error `unexpectedly found nil while unwrapping an Optional value`. I tried to check for nil after getting the array, but it is happening on the line that is getting the array from the UserDefaults, so I don't know how to fix this error. Can anyone help?

```
var classURLs: NSMutableArray = NSMutableArray();
let defaults: NSUserDefaults = NSUserDefaults(suiteName: "group.myCompany.Array")!;
classURLs = NSMutableArray(object: defaults.objectForKey("Class URLs")!);

```