I assume you're talking about a UIButton with UIButtonTypeRoundedRect
?
You can't change the background color of that. When you try changing it's background color you're rather changing the color of the rect the button is drawn on (which is usually clear).
So there are two ways to go. Either you subclass UIButton and overwrite its -drawRect:
method or you create images for the different button states (which is perfectly fine to do).
If you set the background images in Interface Builder you should notice that IB doesn't support setting images for all the states the button can have, so I recommend setting the images in code like this:
UIButton *myButton = [UIButton buttonWithType:UIButtonTypeCustom];
[myButton setBackgroundImage:[UIImage imageNamed:@"normal.png"] forState:UIControlStateNormal];
[myButton setBackgroundImage:[UIImage imageNamed:@"disabled.png"] forState:UIControlStateDisabled];
[myButton setBackgroundImage:[UIImage imageNamed:@"selected.png"] forState:UIControlStateSelected];
[myButton setBackgroundImage:[UIImage imageNamed:@"higligted.png"] forState:UIControlStateHighlighted];
[myButton setBackgroundImage:[UIImage imageNamed:@"highlighted+selected.png"] forState:(UIControlStateHighlighted | UIControlStateSelected)];
The last line shows how to set an image for the selected & highlighted state (that's the one IB can't set).
You don't need the selected images (line 4 & 6) if you're button dosn't need a selected state.