I have created a custom class called PhoneTranslator (based on Xamarin's "Hello, iOS" guide). It looks like this:

```
class PhoneTranslator {
    func ToNumber(raw:String) -> String {
      var newNumber = raw.isEmpty ? "" : raw.uppercaseString
      //newNumber operations...
      return newNumber
    }
}

```

Then I have a ViewController standard class. I want to do this:

```
var translatedNumber : String?

    if let inputText = PhoneNumberTextField.text //getting text from UITextField
    {
        translatedNumber = PhoneTranslator.ToNumber(inputText) //error
    }

```

Then in line with ToNumber method I get an error *Cannot convert value of type 'String' to expected argument type 'PhoneTranslator'*. 

What am I doing wrong? All input and output types seems to match.