Swift helpers for multiple visual constraints

NSLayoutConstraints+visualGroup.swift

extension NSLayoutConstraint {

    public class func visualConstraintsWithMetrics(metrics: [String : CGFloat], views: [String : UIView], options: NSLayoutFormatOptions = nil, strings: String...) -> [NSLayoutConstraint] {
        return map(strings, { string in
            return NSLayoutConstraint.constraintsWithVisualFormat(string, options: options, metrics: metrics, views: views) as [NSLayoutConstraint]
        }).reduce([], +)
    }

    public class func visualConstraintsWithViews(views: [String : UIView], options: NSLayoutFormatOptions = nil, strings: String...) -> [NSLayoutConstraint] {
        return map(strings, { string in
            return NSLayoutConstraint.constraintsWithVisualFormat(string, options: nil, metrics: nil, views: views) as [NSLayoutConstraint]
        }).reduce([], +)
    }

}