Time span repesented as uint instead of TimeSpan

Hi,

I noticed there is a parameter "length" in the method LayoutTo which represent a time span, but its type is uint, shouldn't it be TimeSpan?

http://iosapi.xamarin.com/index.aspx?link=M:Xamarin.Forms.ViewExtensions.LayoutTo(Xamarin.Forms.VisualElement,Xamarin.Forms.Rectangle,System.UInt32,Xamarin.Forms.Easing)

Is there any reason to use uint instead?

Regards,
Alvaro.