A small function to check UIAlertView is shown (based on SO answer: http://stackoverflow.com/a/15151877/1492173)

CheckAlertViewIsShown.swift

private func isAlertExist() -> Bool {
        for window in UIApplication.sharedApplication().windows {
            if let w = window as? UIWindow where w.subviews.count > 0 {
                for subview in w.subviews {
                    if let s = subview as? UIAlertView {
                        return true
                    }
                }
            }
        }
        
        return false
    }