Swift 3 is different from version 2 in the naming department. The short version is that the first label of a function is now mandatory, and that the function signature should reflect this.
Old:
func pageViewsfromContent(content: ENFormContent) -> [VIFormPageView]
New:
func pageViews(fromContent content: ENFormContent) -> [VIFormPageView]
See also: https://swift.org/documentation/api-design-guidelines/