How to remove grey/black border of an UIPicker (iphone)

I am using an UIpicker in a horizontal mode by rotating it 90 degrees. I would like to get rid开发者_如何学Go of the grey/black border surrounding the picker. Is there a way to do that?

Thanks!

I doubt whether we can change the grey/black border surrounding the picker, we can modify the width and height.

Just a thought, Add a UIImageView in front of the UIPickerView which shows the border you need. If this has the problem of selection then add four images on the four side of the square.