Swift 3 Parameter: single variable, two types

Question

Anyone know if there's a way to have a parameter be of two types?

Such as for the function:

func email(from viewcontroller : (UIViewController, MFMailComposeViewControllerDelegate) {

}

Are you looking for the `viewcontroller` parameter to accept types that both inherit from `UIViewController` and conform to `MFMailComposeViewControllerDelegate`? If so, see [Swift: type must implement protocol and be a subclass of given class](http://stackoverflow.com/q/25825988/2976878) — Hamish, Feb 03 '17 at 21:51

score 2 · Accepted Answer · answered Feb 04 '17 at 03:22

2

Genericize your function's definition:

func email<T>(from viewController : T) where T: UIViewController, T: MFMailComposeViewControllerDelegate {
    // ...
}

answered Feb 04 '17 at 03:22

Code Different

score 2 · Answer 2 · answered Feb 28 '19 at 11:36

2

In Swift 4

func email(from viewcontroller : UIViewController & MFMailComposeViewControllerDelegate) {
}

Elegant, short and intuitive.

answered Feb 28 '19 at 11:36

Dark

Unless you try with a `CGFloat & Int` -- _Non-protocol, non-class type 'CGFloat' cannot be used within a protocol-constrained type_ – ruffin Jun 03 '20 at 00:55

2 Answers2