Bound value in a conditional binding must be of Optional Type

Question

I have a protocol defined:

protocol Usable {
    func use()
}

and a class that conforms to that protocol

class Thing: Usabl         


        

Answer 1

You are getting

Bound value in a conditional binding must be of Optional Type

because thing as Usable must return an optional type so making it as? should solved the problem. Unfortunately, the error still persisted for some odd reason. Anyway, a workaround I found to get it to work is to extract out the variable assignment inside the if statement

let thing = Thing()

let usableThing = thing as? Usable

if useableThing { 
    usableThing!.use()
}
else {
    println("can't use that")
}