             case .Trailing, .Bottom:
                 constraints += equalAttributes(views: views, attribute: .Bottom)
             case .FirstBaseline:
-                constraints += equalAttributes(views: views, attribute: .FirstBaseline)
+                if #available(iOS 8.0, *) {
+                    constraints += equalAttributes(views: views, attribute: .FirstBaseline)
+                }
             }
             
         case .Vertical:

    public var spacing: CGFloat = 0
    
    public var layoutMarginsRelativeArrangement = false

    public private(set) var arrangedSubviews: [UIView] = [] {
        didSet {

            }

            if let layoutMarginsView = layoutMarginsView {
                let bottomConstraint: NSLayoutConstraint
                let leftConstraint: NSLayoutConstraint
                let rightConstraint: NSLayoutConstraint
                let topConstraint: NSLayoutConstraint
                if #available(iOS 8.0, *) {
                    bottomConstraint = constraint(item: self, attribute: .BottomMargin, toItem: layoutMarginsView, attribute: .Bottom)
                    leftConstraint = constraint(item: self, attribute: .LeftMargin, toItem: layoutMarginsView, attribute: .Left)
                    rightConstraint = constraint(item: self, attribute: .RightMargin, toItem: layoutMarginsView, attribute: .Right)
                    topConstraint = constraint(item: self, attribute: .TopMargin, toItem: layoutMarginsView, attribute: .Top)
                } else {
                    bottomConstraint = constraint(item: self, attribute: .Bottom, toItem: layoutMarginsView, attribute: .Bottom, constant: _layoutMargins.bottom)
                    leftConstraint = constraint(item: self, attribute: .Left, toItem: layoutMarginsView, attribute: .Left, constant: -_layoutMargins.left)
                    rightConstraint = constraint(item: self, attribute: .Right, toItem: layoutMarginsView, attribute: .Right, constant: _layoutMargins.right)
                    topConstraint = constraint(item: self, attribute: .Top, toItem: layoutMarginsView, attribute: .Top, constant: -_layoutMargins.top)
                }
            
                bottomConstraint.identifier = "TZView-bottomMargin-guide-constraint"
                leftConstraint.identifier = "TZView-leftMargin-guide-constraint"
                rightConstraint.identifier = "TZView-rightMargin-guide-constraint"
                topConstraint.identifier = "TZView-topMargin-guide-constraint"
                stackViewConstraints += [bottomConstraint, leftConstraint, rightConstraint, topConstraint]
            }
            
            addConstraints(stackViewConstraints)
