Replacement for array's indexOf(_:) method in Swift 3

Question

In my project (written in Swift 3) I want to retrieve index of an element from array using indexOf(_:) method (existed in Swift 2.2), but I cannot find any replacem

Answer 1

Didn't work for me in Swift 3 XCode 8 until I gave my class an extension.

For example:

class MyClass {
    var key: String?
}

extension MyClass: Equatable {
    static func == (lhs: MyClass, rhs: MyClass) -> Bool {
        return MyClass.key == MyClass.key
    }
}