Have a variable with multiple types in Swift

Question

I would like to have a variable, which can have multiple types (only ones, I defined), like:

var example: String, Int = 0
example = \"hi\"

Answer 1

Here is how you can achieve it. Works exactly how you'd expect.

protocol StringOrInt { }

extension Int: StringOrInt { }
extension String: StringOrInt { }

var a: StringOrInt = "10"
a = 10 //> 10
a = "q" //> "q"
a = 0.8 //> Error

NB! I would not suggest you to use it in production code. It might be confusing for your teammates.

UPD: as @Martin R mentioned: Note that this restricts the possible types only “by convention.” Any module (or source file) can add a extension MyType: StringOrInt { } conformance.