I am getting the error Fatal error: Unexpectedly found nil while unwrapping an optional value at my line

```
 let pictureRef = self.actStorage.child("\(user.uid).jpg")

```

I know that this is caused by implicitly trying to unwrap an optional which is my

```
     var actStorage: StorageReference!

```

my question is how would I use optional binding or a guard statement so that it is no longer nil?