iphone：使视图透明但子视图不透明

Question

I have a Custom UIViewController named A and i want to add its view to another controllers (named B) view as subview. A's view contain two buttons as subviews. I want to make A's view transparent but the buttons in it nontransparent. I want to know is there any way to do it?

Answer 1

As of I noticed,

If a view is set a opacity/alpha value, all its subviews will be applied with that opacity/alpha value.

Try setting the views background color to [UIColor clearColor]

Answer 2

viewA.backgroundColor = [UIColor clearColor];
[viewA addSubview:button1];
[viewA addSubview:button2];