Separating multiple if conditions with commas in Swift

Question

We already know multiple optional bindings can be used in a single if/guard statement by separating them with commas, but not with && e.g.

Answer 1

Here is a case where they are sufficiently different as to require the ,. The following code will yield

'self' captured by a closure before all members were initialized

class User: NSObject, NSCoding {

    public var profiles: [Profile] = []    
    private var selectedProfileIndex : Int = 0

    public required init?(coder aDecoder: NSCoder) {
        // self.profiles initialized here

        let selectedIndex : Int = 100
        if 0 <= selectedIndex && selectedIndex < self.profiles.count {  <--- error here
            self.selectedProfileIndex = selectedIndex
        }

        super.init()
    }

...
}

This is due to the definition of && on Bool:

static func && (lhs: Bool, rhs: @autoclosure () throws -> Bool) rethrows -> Bool

The selectedIndex < self.profiles.count on the RHS is caught in a closure.

Changing the && to , will get rid of the error. Unfortunately, I'm not sure how , is defined, but I thought that this was interesting.