 #elseif os(OSX)
     typealias View = NSView
 #endif
+    typealias MetricValueType = CGFloat
     
-    public static func constraintsWithVisualFormats(formats: [String], metrics: [String: Double]? = nil, views: [String: View]) -> [NSLayoutConstraint] {
+    public static func constraintsWithVisualFormats(formats: [String], options: NSLayoutFormatOptions = [], metrics: [String: MetricValueType]? = nil, views: [String: View]) -> [NSLayoutConstraint] {
         return formats.reduce([NSLayoutConstraint]()) {
-            $0 + constraintsWithVisualFormat($1, options: [], metrics: metrics, views: views)
+            $0 + constraintsWithVisualFormat($1, options: options, metrics: metrics, views: views)
         }
     }
 }

#elseif os(OSX)
    import AppKit
#endif

public extension NSLayoutConstraint {
#if os(iOS)

}

public extension SequenceType where Generator.Element == String {
    public func constraintsWithViews(views: [String: NSLayoutConstraint.View], options: NSLayoutFormatOptions = [], metrics: [String: NSLayoutConstraint.MetricValueType]? = nil) -> [NSLayoutConstraint] {
        return NSLayoutConstraint.constraintsWithVisualFormats(Array(self), options: options, metrics: metrics, views: views)
    }
}
