如何创建一个从下到上包含0到1不透明度值（alpha值）的UIView？

I want to create a UIView that contains gradually increasing opacity value in it. That is, the UIView's bottom will start with 0.0 as its alpha value and it should end with 1.0 at the top of the UIView. Is it possible to make such view? Or should i separate that view and give them the various alpha value?I want to create a UIView that contains gradual