How to check for `nil` in while loop condition in Swift?

Question

How to check for nil in while loop in Swift? I'm getting error on this:

var count: UInt = 0 var view: UIView = self while view.superview != nil { // Cannot invoke '!=' with an argument list of type '(@lvalue UIView, NilLiteralConvertible)'     count++     view = view.superview } // Here comes count... 

I'm currently using Xcode6-Beta7.

Answer 1

The syntax of while allows for optional binding. Use:

var view: UIView = self while let sv = view.superview {   count += 1   view = sv } 

[Thanks to @ben-leggiero for noting that view need not be Optional (as in the question itself) and for noting Swift 3 incompatibilities]

Answer 2

Your code cannot compile. nil can only appear in optionals. You need to declare view with optional, var view: UIView? = self.superview. Then compare it with nil in the while-loop.

var count: UInt = 0 var view: UIView? = self.superview while view != nil { // Cannot invoke '!=' with an argument list of type '(@lvalue UIView, NilLiteralConvertible)'     count++     view = view!.superview } 

Or do a let binding, But it seems not necessary here, I think.