Here is my class:

```
class Sentence: RLMObject {
    dynamic var words = RLMArray(objectClassName: Word.className())
    dynamic var content = ""

    init(content: String){
        super.init(object: content)
        self.content = content
        let wordArray = makeWordTokens(content)
    }

```

When I try to create a Sentence object like this...

```
let sentence = Sentence(content: "你好吗？")

```

...I get the following runtime error:

```
fatal error: use of unimplemented initializer 'init()' for class 'MyApp.Sentence'

```

Why does it tell me I haven't implemented the initializer? What should I do to fix this?