Setting alpha on UIView sets the alpha on its subviews which should not happen

Setting alpha on UIView sets the alpha on its subviews which should not
happen

According to the documentation for UIVIew @property(nonatomic) CGFloat alpha
The value of this property is a floating-point number in the range 0.0 to
1.0, where 0.0 represents totally transparent and 1.0 represents totally
opaque. This value affects only the current view and does not affect any
of its embedded subviews.
I have a container view configured as follows:
self.myView.backgroundColor = [UIColor blackColor];
self.myView.alpha = 0.5;
[self addSubview:self.myView];
And then add subviews to 'myView'
[myView addSubView anotherView];
anotherView.alpha = 1;
NSLog(@"anotherView alpha = %f",anotherView.alpha); // prints 1.0000 as
expected
But 'anotherView' does have alpha on screen (it is not opaque as expected)
How can this be and what can be done?