Getting "WebDriverWait cannot be resolved to a type" error

Using IOSDriver and running against simulator.

When I make the call:
(new WebDriverWait(driver, timeoutSeconds)).until(ExpectedConditions.elementToBeClickable(By.xpath(locator)))

it never returns. When I execute it in the Eclipse debugger I get:
WebDriverWait cannot be resolved to a type
ExpectedConditions cannot be resolved

When I cast driver to WebDriver, I get the same errors, plus:
WebDriver cannot be resolved to a type

Any ideas?