Extending typed array by conforming to a protocol in Swift 2

Question

I want to extend a typed array Array so that it conforms to a protocol SomeProtocol. Now I know you can extend a typed array like b

Answer 1

In more recent versions of Swift it is possible to write:

extension Array: SomeProtocol where Element == SomeType { ... }

Unsure in which version of Swift this became possible, but the following works in Swift 4.1

class SomeType { }

protocol SomeProtocol {
    func foo()
}

extension Array: SomeProtocol where Element == SomeType {
    func foo() {
        print("foo")
    }
}

let arrayOfSome = [SomeType()]
arrayOfSome.foo() // prints "foo"

let arrayOfInt = [1,2,3]
arrayOfInt.foo() // Will not compile: '[Int]' is not convertible to 'Array'

(I am aware that the question specifically asks for Swift 2, but I am adding this for reference)